May 2009 - developers - lists.mariadb.org

[Maria-developers] New (by Psergey): index_merge optimizer: dont discard index_merge union strategies when range is available (24)
by worklog-noreply＠askmonty.org 26 May '09

26 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: index_merge optimizer: dont discard index_merge union strategies when range is available CREATION DATE..: Tue, 26 May 2009, 12:10 SUPERVISOR.....: Monty IMPLEMENTOR....: Psergey COPIES TO......: Psergey CATEGORY.......: Client-BackLog TASK ID........: 24 (http://askmonty.org/worklog/?tid=24) VERSION........: Benchmarks-3.0 STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: DESCRIPTION: Current range optimizer will discard possible index_merge/[sort]union strategies when there is a possible range plan. This action is a part of measures we take to avoid combinatorial explosion of possible range/ index_merge strategies. A bad side effect of this is that for WHERE clauses in form t.key1= 'very-frequent-value' AND (t.key2='rare-value1' OR t.key3='rare-value2') the optimizer will - discard union(key2,key3) in favor of range(key1) - consider costs of using range(key1) and discard that plan also and the overall effect is that possible poor range access will cause possible good index_merge access not to be considered. This WL is to about lifting this limitation at least for some subset of WHERE clauses. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] [Branch ~maria-captains/maria/5.1] Rev 2705: Fix ps_not_windows test for -all-static build which cannot load plugins.
by noreply＠launchpad.net 22 May '09

22 May '09

------------------------------------------------------------ revno: 2705 committer: knielsen(a)knielsen-hq.org branch nick: work-5.1-buildbot timestamp: Fri 2009-05-22 19:53:25 +0200 message: Fix ps_not_windows test for -all-static build which cannot load plugins. added: mysql-test/include/have_dynamic_loading.inc modified: mysql-test/t/ps_not_windows.test === added file 'mysql-test/include/have_dynamic_loading.inc' --- mysql-test/include/have_dynamic_loading.inc 1970-01-01 00:00:00 +0000 +++ mysql-test/include/have_dynamic_loading.inc 2009-05-22 17:53:25 +0000 @@ -0,0 +1,4 @@ +-- require r/have_dynamic_loading.require +disable_query_log; +show variables like 'have_dynamic_loading'; +enable_query_log; === modified file 'mysql-test/t/ps_not_windows.test' --- mysql-test/t/ps_not_windows.test 2007-01-02 23:31:12 +0000 +++ mysql-test/t/ps_not_windows.test 2009-05-22 17:53:25 +0000 @@ -2,6 +2,8 @@ --source include/not_embedded.inc # Non-windows specific ps tests. --source include/not_windows.inc +# Requires ability to install plugins. +--source include/have_dynamic_loading.inc # # Bug #20665: All commands supported in Stored Procedures should work in -- Main stable branch https://code.launchpad.net/~maria-captains/maria/5.1 Your team Maria developers is subscribed to branch lp:maria. To unsubscribe from this branch go to https://code.launchpad.net/~maria-captains/maria/5.1/+edit-subscription.

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[Maria-developers] bzr commit into MariaDB 5.1, with Maria 1.5:maria branch (knielsen:2705)
by knielsen＠knielsen-hq.org 22 May '09

22 May '09

#At lp:maria 2705 knielsen(a)knielsen-hq.org 2009-05-22 Fix ps_not_windows test for -all-static build which cannot load plugins. added: mysql-test/include/have_dynamic_loading.inc modified: mysql-test/t/ps_not_windows.test === added file 'mysql-test/include/have_dynamic_loading.inc' --- a/mysql-test/include/have_dynamic_loading.inc 1970-01-01 00:00:00 +0000 +++ b/mysql-test/include/have_dynamic_loading.inc 2009-05-22 17:53:25 +0000 @@ -0,0 +1,4 @@ +-- require r/have_dynamic_loading.require +disable_query_log; +show variables like 'have_dynamic_loading'; +enable_query_log; === modified file 'mysql-test/t/ps_not_windows.test' --- a/mysql-test/t/ps_not_windows.test 2007-01-02 23:31:12 +0000 +++ b/mysql-test/t/ps_not_windows.test 2009-05-22 17:53:25 +0000 @@ -2,6 +2,8 @@ --source include/not_embedded.inc # Non-windows specific ps tests. --source include/not_windows.inc +# Requires ability to install plugins. +--source include/have_dynamic_loading.inc # # Bug #20665: All commands supported in Stored Procedures should work in

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[Maria-developers] Updated (by Guest): Table Elimination: remove the facts table (20)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table Elimination: remove the facts table CREATION DATE..: Thu, 21 May 2009, 01:07 SUPERVISOR.....: Monty IMPLEMENTOR....: Psergey COPIES TO......: Psergey CATEGORY.......: Server-BackLog TASK ID........: 20 (http://askmonty.org/worklog/?tid=20) VERSION........: Server-5.2 STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:51)=-=- Version updated. --- /tmp/wklog.20.old.31642 2009-05-22 17:51:21.000000000 +0300 +++ /tmp/wklog.20.new.31642 2009-05-22 17:51:21.000000000 +0300 @@ -1 +1 @@ -Server-9.x +Server-5.2 -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Category updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Server-RawIdeaBin +Server-BackLog -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Status updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Un-Assigned +Assigned -=-=(Guest - Fri, 22 May 2009, 17:29)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.31038 2009-05-22 17:29:58.000000000 +0300 +++ /tmp/wklog.20.new.31038 2009-05-22 17:29:58.000000000 +0300 @@ -68,7 +68,7 @@ where ACBDT_Birthdate < '1950-01-01' -At this point, it's possible to conclude that table anchor can be removed from +At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( @@ -80,6 +80,18 @@ mean actors that have NULL/no names), but we're not interested in those as it is an inner join. +The result is (notice the changed select): + +select + actor_birthday.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor_birthdate + left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + How to remove ------------- * Find inner joins, such that -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.28489 2009-05-21 22:54:52.000000000 +0300 +++ /tmp/wklog.20.new.28489 2009-05-21 22:54:52.000000000 +0300 @@ -11,7 +11,7 @@ -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( - AC_ID primary key, + AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), @@ -21,7 +21,7 @@ -- Another physical attribute: actor birthdate -- create table actor_birthdate ( - AC_ID primary key, + AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) -=-=(Psergey - Thu, 21 May 2009, 01:07)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.26317 2009-05-21 01:07:55.000000000 +0300 +++ /tmp/wklog.20.new.26317 2009-05-21 01:07:55.000000000 +0300 @@ -1 +1,91 @@ +Consider the following schema: + +-- +-- The physical anchor table +-- +create table actor ( + AC_ID int primary key +); + +-- +-- A physical attribute: actor name (non-historized for simplicity) +-- +create table actor_name ( + AC_ID primary key, + ACNAM_Name varchar(20), + index(ACNAM_Name), + foreign key (AC_ID) references actor(AC_ID), +); + +-- +-- Another physical attribute: actor birthdate +-- +create table actor_birthdate ( + AC_ID primary key, + ACBDT_Birthdate datetime, + index(ACBDT_Birthdate), + foreign key (AC_ID) references actor(AC_ID) +); + +-- +-- The knot view: actor with its attributes +-- +create view actor_attributes as +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate + ... (other attributes follow) +from + actor + left join actor_name on (actor_name.AC_ID = actor.AC_ID) + left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + ... other attributes follow ... +; + +-- The query: names of senior actors +select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' + +Query processing +---------------- +The following steps will occur +* The VIEW will be resolved with algorithm=merge +* Outer-to-inner join conversion will make use of the + ACBDT_Birthdate < '1950-01-01' condition and change one outer join into + inner. +* Table elimination variant#1 will remove all unused attributes. + +And we'll end up with: + +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor + join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + left join actor_name on (actor_name.AC_ID = actor.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + +At this point, it's possible to conclude that table anchor can be removed from +the query plan: anchor model specifies that actor_name has a foreign key: + + create table actor_name ( + ... + foreign key (AC_ID) references actor(AC_ID), + +This means that each record in actor_name has exactly one match in table actor. +There may be records in `actor` that have no matches in `actor_name` (they +mean actors that have NULL/no names), but we're not interested in those as it +is an inner join. + +How to remove +------------- +* Find inner joins, such that + - some table T can be accessed using eq_ref access method. + - some other table T2 has Foreign Key that refers to table T. + - there are no references to table T anywhere in the query, except for + references to T.primary_key, which can be substituted for columns of T2. + DESCRIPTION: In certain cases it is possible to eliminate table when one is running inner joins and there is a foreign key relationship between the tables. HIGH-LEVEL SPECIFICATION: Consider the following schema: -- -- The physical anchor table -- create table actor ( AC_ID int primary key ); -- -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), ); -- -- Another physical attribute: actor birthdate -- create table actor_birthdate ( AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) ); -- -- The knot view: actor with its attributes -- create view actor_attributes as select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate ... (other attributes follow) from actor left join actor_name on (actor_name.AC_ID = actor.AC_ID) left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) ... other attributes follow ... ; -- The query: names of senior actors select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' Query processing ---------------- The following steps will occur * The VIEW will be resolved with algorithm=merge * Outer-to-inner join conversion will make use of the ACBDT_Birthdate < '1950-01-01' condition and change one outer join into inner. * Table elimination variant#1 will remove all unused attributes. And we'll end up with: select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) left join actor_name on (actor_name.AC_ID = actor.AC_ID) where ACBDT_Birthdate < '1950-01-01' At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( ... foreign key (AC_ID) references actor(AC_ID), This means that each record in actor_name has exactly one match in table actor. There may be records in `actor` that have no matches in `actor_name` (they mean actors that have NULL/no names), but we're not interested in those as it is an inner join. The result is (notice the changed select): select actor_birthday.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor_birthdate left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) where ACBDT_Birthdate < '1950-01-01' How to remove ------------- * Find inner joins, such that - some table T can be accessed using eq_ref access method. - some other table T2 has Foreign Key that refers to table T. - there are no references to table T anywhere in the query, except for references to T.primary_key, which can be substituted for columns of T2. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Guest): Table Elimination: remove the facts table (20)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table Elimination: remove the facts table CREATION DATE..: Thu, 21 May 2009, 01:07 SUPERVISOR.....: Monty IMPLEMENTOR....: Psergey COPIES TO......: Psergey CATEGORY.......: Server-BackLog TASK ID........: 20 (http://askmonty.org/worklog/?tid=20) VERSION........: Server-5.2 STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:51)=-=- Version updated. --- /tmp/wklog.20.old.31642 2009-05-22 17:51:21.000000000 +0300 +++ /tmp/wklog.20.new.31642 2009-05-22 17:51:21.000000000 +0300 @@ -1 +1 @@ -Server-9.x +Server-5.2 -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Category updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Server-RawIdeaBin +Server-BackLog -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Status updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Un-Assigned +Assigned -=-=(Guest - Fri, 22 May 2009, 17:29)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.31038 2009-05-22 17:29:58.000000000 +0300 +++ /tmp/wklog.20.new.31038 2009-05-22 17:29:58.000000000 +0300 @@ -68,7 +68,7 @@ where ACBDT_Birthdate < '1950-01-01' -At this point, it's possible to conclude that table anchor can be removed from +At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( @@ -80,6 +80,18 @@ mean actors that have NULL/no names), but we're not interested in those as it is an inner join. +The result is (notice the changed select): + +select + actor_birthday.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor_birthdate + left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + How to remove ------------- * Find inner joins, such that -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.28489 2009-05-21 22:54:52.000000000 +0300 +++ /tmp/wklog.20.new.28489 2009-05-21 22:54:52.000000000 +0300 @@ -11,7 +11,7 @@ -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( - AC_ID primary key, + AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), @@ -21,7 +21,7 @@ -- Another physical attribute: actor birthdate -- create table actor_birthdate ( - AC_ID primary key, + AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) -=-=(Psergey - Thu, 21 May 2009, 01:07)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.26317 2009-05-21 01:07:55.000000000 +0300 +++ /tmp/wklog.20.new.26317 2009-05-21 01:07:55.000000000 +0300 @@ -1 +1,91 @@ +Consider the following schema: + +-- +-- The physical anchor table +-- +create table actor ( + AC_ID int primary key +); + +-- +-- A physical attribute: actor name (non-historized for simplicity) +-- +create table actor_name ( + AC_ID primary key, + ACNAM_Name varchar(20), + index(ACNAM_Name), + foreign key (AC_ID) references actor(AC_ID), +); + +-- +-- Another physical attribute: actor birthdate +-- +create table actor_birthdate ( + AC_ID primary key, + ACBDT_Birthdate datetime, + index(ACBDT_Birthdate), + foreign key (AC_ID) references actor(AC_ID) +); + +-- +-- The knot view: actor with its attributes +-- +create view actor_attributes as +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate + ... (other attributes follow) +from + actor + left join actor_name on (actor_name.AC_ID = actor.AC_ID) + left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + ... other attributes follow ... +; + +-- The query: names of senior actors +select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' + +Query processing +---------------- +The following steps will occur +* The VIEW will be resolved with algorithm=merge +* Outer-to-inner join conversion will make use of the + ACBDT_Birthdate < '1950-01-01' condition and change one outer join into + inner. +* Table elimination variant#1 will remove all unused attributes. + +And we'll end up with: + +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor + join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + left join actor_name on (actor_name.AC_ID = actor.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + +At this point, it's possible to conclude that table anchor can be removed from +the query plan: anchor model specifies that actor_name has a foreign key: + + create table actor_name ( + ... + foreign key (AC_ID) references actor(AC_ID), + +This means that each record in actor_name has exactly one match in table actor. +There may be records in `actor` that have no matches in `actor_name` (they +mean actors that have NULL/no names), but we're not interested in those as it +is an inner join. + +How to remove +------------- +* Find inner joins, such that + - some table T can be accessed using eq_ref access method. + - some other table T2 has Foreign Key that refers to table T. + - there are no references to table T anywhere in the query, except for + references to T.primary_key, which can be substituted for columns of T2. + DESCRIPTION: In certain cases it is possible to eliminate table when one is running inner joins and there is a foreign key relationship between the tables. HIGH-LEVEL SPECIFICATION: Consider the following schema: -- -- The physical anchor table -- create table actor ( AC_ID int primary key ); -- -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), ); -- -- Another physical attribute: actor birthdate -- create table actor_birthdate ( AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) ); -- -- The knot view: actor with its attributes -- create view actor_attributes as select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate ... (other attributes follow) from actor left join actor_name on (actor_name.AC_ID = actor.AC_ID) left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) ... other attributes follow ... ; -- The query: names of senior actors select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' Query processing ---------------- The following steps will occur * The VIEW will be resolved with algorithm=merge * Outer-to-inner join conversion will make use of the ACBDT_Birthdate < '1950-01-01' condition and change one outer join into inner. * Table elimination variant#1 will remove all unused attributes. And we'll end up with: select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) left join actor_name on (actor_name.AC_ID = actor.AC_ID) where ACBDT_Birthdate < '1950-01-01' At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( ... foreign key (AC_ID) references actor(AC_ID), This means that each record in actor_name has exactly one match in table actor. There may be records in `actor` that have no matches in `actor_name` (they mean actors that have NULL/no names), but we're not interested in those as it is an inner join. The result is (notice the changed select): select actor_birthday.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor_birthdate left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) where ACBDT_Birthdate < '1950-01-01' How to remove ------------- * Find inner joins, such that - some table T can be accessed using eq_ref access method. - some other table T2 has Foreign Key that refers to table T. - there are no references to table T anywhere in the query, except for references to T.primary_key, which can be substituted for columns of T2. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Guest): Table Elimination: remove the facts table (20)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table Elimination: remove the facts table CREATION DATE..: Thu, 21 May 2009, 01:07 SUPERVISOR.....: Monty IMPLEMENTOR....: Psergey COPIES TO......: Psergey CATEGORY.......: Server-BackLog TASK ID........: 20 (http://askmonty.org/worklog/?tid=20) VERSION........: Server-9.x STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Category updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Server-RawIdeaBin +Server-BackLog -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Status updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Un-Assigned +Assigned -=-=(Guest - Fri, 22 May 2009, 17:29)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.31038 2009-05-22 17:29:58.000000000 +0300 +++ /tmp/wklog.20.new.31038 2009-05-22 17:29:58.000000000 +0300 @@ -68,7 +68,7 @@ where ACBDT_Birthdate < '1950-01-01' -At this point, it's possible to conclude that table anchor can be removed from +At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( @@ -80,6 +80,18 @@ mean actors that have NULL/no names), but we're not interested in those as it is an inner join. +The result is (notice the changed select): + +select + actor_birthday.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor_birthdate + left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + How to remove ------------- * Find inner joins, such that -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.28489 2009-05-21 22:54:52.000000000 +0300 +++ /tmp/wklog.20.new.28489 2009-05-21 22:54:52.000000000 +0300 @@ -11,7 +11,7 @@ -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( - AC_ID primary key, + AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), @@ -21,7 +21,7 @@ -- Another physical attribute: actor birthdate -- create table actor_birthdate ( - AC_ID primary key, + AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) -=-=(Psergey - Thu, 21 May 2009, 01:07)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.26317 2009-05-21 01:07:55.000000000 +0300 +++ /tmp/wklog.20.new.26317 2009-05-21 01:07:55.000000000 +0300 @@ -1 +1,91 @@ +Consider the following schema: + +-- +-- The physical anchor table +-- +create table actor ( + AC_ID int primary key +); + +-- +-- A physical attribute: actor name (non-historized for simplicity) +-- +create table actor_name ( + AC_ID primary key, + ACNAM_Name varchar(20), + index(ACNAM_Name), + foreign key (AC_ID) references actor(AC_ID), +); + +-- +-- Another physical attribute: actor birthdate +-- +create table actor_birthdate ( + AC_ID primary key, + ACBDT_Birthdate datetime, + index(ACBDT_Birthdate), + foreign key (AC_ID) references actor(AC_ID) +); + +-- +-- The knot view: actor with its attributes +-- +create view actor_attributes as +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate + ... (other attributes follow) +from + actor + left join actor_name on (actor_name.AC_ID = actor.AC_ID) + left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + ... other attributes follow ... +; + +-- The query: names of senior actors +select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' + +Query processing +---------------- +The following steps will occur +* The VIEW will be resolved with algorithm=merge +* Outer-to-inner join conversion will make use of the + ACBDT_Birthdate < '1950-01-01' condition and change one outer join into + inner. +* Table elimination variant#1 will remove all unused attributes. + +And we'll end up with: + +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor + join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + left join actor_name on (actor_name.AC_ID = actor.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + +At this point, it's possible to conclude that table anchor can be removed from +the query plan: anchor model specifies that actor_name has a foreign key: + + create table actor_name ( + ... + foreign key (AC_ID) references actor(AC_ID), + +This means that each record in actor_name has exactly one match in table actor. +There may be records in `actor` that have no matches in `actor_name` (they +mean actors that have NULL/no names), but we're not interested in those as it +is an inner join. + +How to remove +------------- +* Find inner joins, such that + - some table T can be accessed using eq_ref access method. + - some other table T2 has Foreign Key that refers to table T. + - there are no references to table T anywhere in the query, except for + references to T.primary_key, which can be substituted for columns of T2. + DESCRIPTION: In certain cases it is possible to eliminate table when one is running inner joins and there is a foreign key relationship between the tables. HIGH-LEVEL SPECIFICATION: Consider the following schema: -- -- The physical anchor table -- create table actor ( AC_ID int primary key ); -- -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), ); -- -- Another physical attribute: actor birthdate -- create table actor_birthdate ( AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) ); -- -- The knot view: actor with its attributes -- create view actor_attributes as select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate ... (other attributes follow) from actor left join actor_name on (actor_name.AC_ID = actor.AC_ID) left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) ... other attributes follow ... ; -- The query: names of senior actors select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' Query processing ---------------- The following steps will occur * The VIEW will be resolved with algorithm=merge * Outer-to-inner join conversion will make use of the ACBDT_Birthdate < '1950-01-01' condition and change one outer join into inner. * Table elimination variant#1 will remove all unused attributes. And we'll end up with: select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) left join actor_name on (actor_name.AC_ID = actor.AC_ID) where ACBDT_Birthdate < '1950-01-01' At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( ... foreign key (AC_ID) references actor(AC_ID), This means that each record in actor_name has exactly one match in table actor. There may be records in `actor` that have no matches in `actor_name` (they mean actors that have NULL/no names), but we're not interested in those as it is an inner join. The result is (notice the changed select): select actor_birthday.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor_birthdate left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) where ACBDT_Birthdate < '1950-01-01' How to remove ------------- * Find inner joins, such that - some table T can be accessed using eq_ref access method. - some other table T2 has Foreign Key that refers to table T. - there are no references to table T anywhere in the query, except for references to T.primary_key, which can be substituted for columns of T2. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Guest): Table Elimination: remove the facts table (20)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table Elimination: remove the facts table CREATION DATE..: Thu, 21 May 2009, 01:07 SUPERVISOR.....: Monty IMPLEMENTOR....: Psergey COPIES TO......: Psergey CATEGORY.......: Server-BackLog TASK ID........: 20 (http://askmonty.org/worklog/?tid=20) VERSION........: Server-9.x STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Category updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Server-RawIdeaBin +Server-BackLog -=-=(Guest - Fri, 22 May 2009, 17:50)=-=- Status updated. --- /tmp/wklog.20.old.31598 2009-05-22 17:50:49.000000000 +0300 +++ /tmp/wklog.20.new.31598 2009-05-22 17:50:49.000000000 +0300 @@ -1 +1 @@ -Un-Assigned +Assigned -=-=(Guest - Fri, 22 May 2009, 17:29)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.31038 2009-05-22 17:29:58.000000000 +0300 +++ /tmp/wklog.20.new.31038 2009-05-22 17:29:58.000000000 +0300 @@ -68,7 +68,7 @@ where ACBDT_Birthdate < '1950-01-01' -At this point, it's possible to conclude that table anchor can be removed from +At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( @@ -80,6 +80,18 @@ mean actors that have NULL/no names), but we're not interested in those as it is an inner join. +The result is (notice the changed select): + +select + actor_birthday.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor_birthdate + left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + How to remove ------------- * Find inner joins, such that -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.28489 2009-05-21 22:54:52.000000000 +0300 +++ /tmp/wklog.20.new.28489 2009-05-21 22:54:52.000000000 +0300 @@ -11,7 +11,7 @@ -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( - AC_ID primary key, + AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), @@ -21,7 +21,7 @@ -- Another physical attribute: actor birthdate -- create table actor_birthdate ( - AC_ID primary key, + AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) -=-=(Psergey - Thu, 21 May 2009, 01:07)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.26317 2009-05-21 01:07:55.000000000 +0300 +++ /tmp/wklog.20.new.26317 2009-05-21 01:07:55.000000000 +0300 @@ -1 +1,91 @@ +Consider the following schema: + +-- +-- The physical anchor table +-- +create table actor ( + AC_ID int primary key +); + +-- +-- A physical attribute: actor name (non-historized for simplicity) +-- +create table actor_name ( + AC_ID primary key, + ACNAM_Name varchar(20), + index(ACNAM_Name), + foreign key (AC_ID) references actor(AC_ID), +); + +-- +-- Another physical attribute: actor birthdate +-- +create table actor_birthdate ( + AC_ID primary key, + ACBDT_Birthdate datetime, + index(ACBDT_Birthdate), + foreign key (AC_ID) references actor(AC_ID) +); + +-- +-- The knot view: actor with its attributes +-- +create view actor_attributes as +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate + ... (other attributes follow) +from + actor + left join actor_name on (actor_name.AC_ID = actor.AC_ID) + left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + ... other attributes follow ... +; + +-- The query: names of senior actors +select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' + +Query processing +---------------- +The following steps will occur +* The VIEW will be resolved with algorithm=merge +* Outer-to-inner join conversion will make use of the + ACBDT_Birthdate < '1950-01-01' condition and change one outer join into + inner. +* Table elimination variant#1 will remove all unused attributes. + +And we'll end up with: + +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor + join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + left join actor_name on (actor_name.AC_ID = actor.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + +At this point, it's possible to conclude that table anchor can be removed from +the query plan: anchor model specifies that actor_name has a foreign key: + + create table actor_name ( + ... + foreign key (AC_ID) references actor(AC_ID), + +This means that each record in actor_name has exactly one match in table actor. +There may be records in `actor` that have no matches in `actor_name` (they +mean actors that have NULL/no names), but we're not interested in those as it +is an inner join. + +How to remove +------------- +* Find inner joins, such that + - some table T can be accessed using eq_ref access method. + - some other table T2 has Foreign Key that refers to table T. + - there are no references to table T anywhere in the query, except for + references to T.primary_key, which can be substituted for columns of T2. + DESCRIPTION: In certain cases it is possible to eliminate table when one is running inner joins and there is a foreign key relationship between the tables. HIGH-LEVEL SPECIFICATION: Consider the following schema: -- -- The physical anchor table -- create table actor ( AC_ID int primary key ); -- -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), ); -- -- Another physical attribute: actor birthdate -- create table actor_birthdate ( AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) ); -- -- The knot view: actor with its attributes -- create view actor_attributes as select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate ... (other attributes follow) from actor left join actor_name on (actor_name.AC_ID = actor.AC_ID) left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) ... other attributes follow ... ; -- The query: names of senior actors select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' Query processing ---------------- The following steps will occur * The VIEW will be resolved with algorithm=merge * Outer-to-inner join conversion will make use of the ACBDT_Birthdate < '1950-01-01' condition and change one outer join into inner. * Table elimination variant#1 will remove all unused attributes. And we'll end up with: select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) left join actor_name on (actor_name.AC_ID = actor.AC_ID) where ACBDT_Birthdate < '1950-01-01' At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( ... foreign key (AC_ID) references actor(AC_ID), This means that each record in actor_name has exactly one match in table actor. There may be records in `actor` that have no matches in `actor_name` (they mean actors that have NULL/no names), but we're not interested in those as it is an inner join. The result is (notice the changed select): select actor_birthday.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor_birthdate left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) where ACBDT_Birthdate < '1950-01-01' How to remove ------------- * Find inner joins, such that - some table T can be accessed using eq_ref access method. - some other table T2 has Foreign Key that refers to table T. - there are no references to table T anywhere in the query, except for references to T.primary_key, which can be substituted for columns of T2. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Updated (by Guest): Table Elimination: remove the facts table (20)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table Elimination: remove the facts table CREATION DATE..: Thu, 21 May 2009, 01:07 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Psergey CATEGORY.......: Server-RawIdeaBin TASK ID........: 20 (http://askmonty.org/worklog/?tid=20) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:29)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.31038 2009-05-22 17:29:58.000000000 +0300 +++ /tmp/wklog.20.new.31038 2009-05-22 17:29:58.000000000 +0300 @@ -68,7 +68,7 @@ where ACBDT_Birthdate < '1950-01-01' -At this point, it's possible to conclude that table anchor can be removed from +At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( @@ -80,6 +80,18 @@ mean actors that have NULL/no names), but we're not interested in those as it is an inner join. +The result is (notice the changed select): + +select + actor_birthday.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor_birthdate + left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + How to remove ------------- * Find inner joins, such that -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.28489 2009-05-21 22:54:52.000000000 +0300 +++ /tmp/wklog.20.new.28489 2009-05-21 22:54:52.000000000 +0300 @@ -11,7 +11,7 @@ -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( - AC_ID primary key, + AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), @@ -21,7 +21,7 @@ -- Another physical attribute: actor birthdate -- create table actor_birthdate ( - AC_ID primary key, + AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) -=-=(Psergey - Thu, 21 May 2009, 01:07)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.26317 2009-05-21 01:07:55.000000000 +0300 +++ /tmp/wklog.20.new.26317 2009-05-21 01:07:55.000000000 +0300 @@ -1 +1,91 @@ +Consider the following schema: + +-- +-- The physical anchor table +-- +create table actor ( + AC_ID int primary key +); + +-- +-- A physical attribute: actor name (non-historized for simplicity) +-- +create table actor_name ( + AC_ID primary key, + ACNAM_Name varchar(20), + index(ACNAM_Name), + foreign key (AC_ID) references actor(AC_ID), +); + +-- +-- Another physical attribute: actor birthdate +-- +create table actor_birthdate ( + AC_ID primary key, + ACBDT_Birthdate datetime, + index(ACBDT_Birthdate), + foreign key (AC_ID) references actor(AC_ID) +); + +-- +-- The knot view: actor with its attributes +-- +create view actor_attributes as +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate + ... (other attributes follow) +from + actor + left join actor_name on (actor_name.AC_ID = actor.AC_ID) + left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + ... other attributes follow ... +; + +-- The query: names of senior actors +select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' + +Query processing +---------------- +The following steps will occur +* The VIEW will be resolved with algorithm=merge +* Outer-to-inner join conversion will make use of the + ACBDT_Birthdate < '1950-01-01' condition and change one outer join into + inner. +* Table elimination variant#1 will remove all unused attributes. + +And we'll end up with: + +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor + join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + left join actor_name on (actor_name.AC_ID = actor.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + +At this point, it's possible to conclude that table anchor can be removed from +the query plan: anchor model specifies that actor_name has a foreign key: + + create table actor_name ( + ... + foreign key (AC_ID) references actor(AC_ID), + +This means that each record in actor_name has exactly one match in table actor. +There may be records in `actor` that have no matches in `actor_name` (they +mean actors that have NULL/no names), but we're not interested in those as it +is an inner join. + +How to remove +------------- +* Find inner joins, such that + - some table T can be accessed using eq_ref access method. + - some other table T2 has Foreign Key that refers to table T. + - there are no references to table T anywhere in the query, except for + references to T.primary_key, which can be substituted for columns of T2. + DESCRIPTION: In certain cases it is possible to eliminate table when one is running inner joins and there is a foreign key relationship between the tables. HIGH-LEVEL SPECIFICATION: Consider the following schema: -- -- The physical anchor table -- create table actor ( AC_ID int primary key ); -- -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), ); -- -- Another physical attribute: actor birthdate -- create table actor_birthdate ( AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) ); -- -- The knot view: actor with its attributes -- create view actor_attributes as select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate ... (other attributes follow) from actor left join actor_name on (actor_name.AC_ID = actor.AC_ID) left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) ... other attributes follow ... ; -- The query: names of senior actors select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' Query processing ---------------- The following steps will occur * The VIEW will be resolved with algorithm=merge * Outer-to-inner join conversion will make use of the ACBDT_Birthdate < '1950-01-01' condition and change one outer join into inner. * Table elimination variant#1 will remove all unused attributes. And we'll end up with: select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) left join actor_name on (actor_name.AC_ID = actor.AC_ID) where ACBDT_Birthdate < '1950-01-01' At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( ... foreign key (AC_ID) references actor(AC_ID), This means that each record in actor_name has exactly one match in table actor. There may be records in `actor` that have no matches in `actor_name` (they mean actors that have NULL/no names), but we're not interested in those as it is an inner join. The result is (notice the changed select): select actor_birthday.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor_birthdate left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) where ACBDT_Birthdate < '1950-01-01' How to remove ------------- * Find inner joins, such that - some table T can be accessed using eq_ref access method. - some other table T2 has Foreign Key that refers to table T. - there are no references to table T anywhere in the query, except for references to T.primary_key, which can be substituted for columns of T2. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Updated (by Guest): Table Elimination: remove the facts table (20)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table Elimination: remove the facts table CREATION DATE..: Thu, 21 May 2009, 01:07 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Psergey CATEGORY.......: Server-RawIdeaBin TASK ID........: 20 (http://askmonty.org/worklog/?tid=20) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:29)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.31038 2009-05-22 17:29:58.000000000 +0300 +++ /tmp/wklog.20.new.31038 2009-05-22 17:29:58.000000000 +0300 @@ -68,7 +68,7 @@ where ACBDT_Birthdate < '1950-01-01' -At this point, it's possible to conclude that table anchor can be removed from +At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( @@ -80,6 +80,18 @@ mean actors that have NULL/no names), but we're not interested in those as it is an inner join. +The result is (notice the changed select): + +select + actor_birthday.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor_birthdate + left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + How to remove ------------- * Find inner joins, such that -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.28489 2009-05-21 22:54:52.000000000 +0300 +++ /tmp/wklog.20.new.28489 2009-05-21 22:54:52.000000000 +0300 @@ -11,7 +11,7 @@ -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( - AC_ID primary key, + AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), @@ -21,7 +21,7 @@ -- Another physical attribute: actor birthdate -- create table actor_birthdate ( - AC_ID primary key, + AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) -=-=(Psergey - Thu, 21 May 2009, 01:07)=-=- High-Level Specification modified. --- /tmp/wklog.20.old.26317 2009-05-21 01:07:55.000000000 +0300 +++ /tmp/wklog.20.new.26317 2009-05-21 01:07:55.000000000 +0300 @@ -1 +1,91 @@ +Consider the following schema: + +-- +-- The physical anchor table +-- +create table actor ( + AC_ID int primary key +); + +-- +-- A physical attribute: actor name (non-historized for simplicity) +-- +create table actor_name ( + AC_ID primary key, + ACNAM_Name varchar(20), + index(ACNAM_Name), + foreign key (AC_ID) references actor(AC_ID), +); + +-- +-- Another physical attribute: actor birthdate +-- +create table actor_birthdate ( + AC_ID primary key, + ACBDT_Birthdate datetime, + index(ACBDT_Birthdate), + foreign key (AC_ID) references actor(AC_ID) +); + +-- +-- The knot view: actor with its attributes +-- +create view actor_attributes as +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate + ... (other attributes follow) +from + actor + left join actor_name on (actor_name.AC_ID = actor.AC_ID) + left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + ... other attributes follow ... +; + +-- The query: names of senior actors +select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' + +Query processing +---------------- +The following steps will occur +* The VIEW will be resolved with algorithm=merge +* Outer-to-inner join conversion will make use of the + ACBDT_Birthdate < '1950-01-01' condition and change one outer join into + inner. +* Table elimination variant#1 will remove all unused attributes. + +And we'll end up with: + +select + actor.AC_ID, + actor_name.ACNAM_Name, + actor_birthdate.ACBDT_Birthdate +from + actor + join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) + left join actor_name on (actor_name.AC_ID = actor.AC_ID) +where + ACBDT_Birthdate < '1950-01-01' + +At this point, it's possible to conclude that table anchor can be removed from +the query plan: anchor model specifies that actor_name has a foreign key: + + create table actor_name ( + ... + foreign key (AC_ID) references actor(AC_ID), + +This means that each record in actor_name has exactly one match in table actor. +There may be records in `actor` that have no matches in `actor_name` (they +mean actors that have NULL/no names), but we're not interested in those as it +is an inner join. + +How to remove +------------- +* Find inner joins, such that + - some table T can be accessed using eq_ref access method. + - some other table T2 has Foreign Key that refers to table T. + - there are no references to table T anywhere in the query, except for + references to T.primary_key, which can be substituted for columns of T2. + DESCRIPTION: In certain cases it is possible to eliminate table when one is running inner joins and there is a foreign key relationship between the tables. HIGH-LEVEL SPECIFICATION: Consider the following schema: -- -- The physical anchor table -- create table actor ( AC_ID int primary key ); -- -- A physical attribute: actor name (non-historized for simplicity) -- create table actor_name ( AC_ID int primary key, ACNAM_Name varchar(20), index(ACNAM_Name), foreign key (AC_ID) references actor(AC_ID), ); -- -- Another physical attribute: actor birthdate -- create table actor_birthdate ( AC_ID int primary key, ACBDT_Birthdate datetime, index(ACBDT_Birthdate), foreign key (AC_ID) references actor(AC_ID) ); -- -- The knot view: actor with its attributes -- create view actor_attributes as select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate ... (other attributes follow) from actor left join actor_name on (actor_name.AC_ID = actor.AC_ID) left join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) ... other attributes follow ... ; -- The query: names of senior actors select ACNAM_Name from actor_attributes where ACBDT_Birthdate < '1950-01-01' Query processing ---------------- The following steps will occur * The VIEW will be resolved with algorithm=merge * Outer-to-inner join conversion will make use of the ACBDT_Birthdate < '1950-01-01' condition and change one outer join into inner. * Table elimination variant#1 will remove all unused attributes. And we'll end up with: select actor.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor join actor_birthdate on (actor_birthdate.AC_ID = actor.AC_ID) left join actor_name on (actor_name.AC_ID = actor.AC_ID) where ACBDT_Birthdate < '1950-01-01' At this point, it's possible to conclude that table actor can be removed from the query plan: anchor model specifies that actor_name has a foreign key: create table actor_name ( ... foreign key (AC_ID) references actor(AC_ID), This means that each record in actor_name has exactly one match in table actor. There may be records in `actor` that have no matches in `actor_name` (they mean actors that have NULL/no names), but we're not interested in those as it is an inner join. The result is (notice the changed select): select actor_birthday.AC_ID, actor_name.ACNAM_Name, actor_birthdate.ACBDT_Birthdate from actor_birthdate left join actor_name on (actor_name.AC_ID = actor_birthday.AC_ID) where ACBDT_Birthdate < '1950-01-01' How to remove ------------- * Find inner joins, such that - some table T can be accessed using eq_ref access method. - some other table T2 has Foreign Key that refers to table T. - there are no references to table T anywhere in the query, except for references to T.primary_key, which can be substituted for columns of T2. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Guest): Table elimination (17)
by worklog-noreply＠askmonty.org 22 May '09

22 May '09

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Table elimination CREATION DATE..: Sun, 10 May 2009, 19:57 SUPERVISOR.....: Monty IMPLEMENTOR....: Psergey COPIES TO......: CATEGORY.......: Server-Sprint TASK ID........: 17 (http://askmonty.org/worklog/?tid=17) VERSION........: Server-5.1 STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Fri, 22 May 2009, 17:23)=-=- High-Level Specification modified. --- /tmp/wklog.17.old.30851 2009-05-22 17:23:38.000000000 +0300 +++ /tmp/wklog.17.new.30851 2009-05-22 17:23:38.000000000 +0300 @@ -6,7 +6,7 @@ elimination but not to the same extent. Basically, what table elimination does, is to remove tables from the -execution plan when it is unneccessary to include them. This can, of +execution plan when it is unnecessary to include them. This can, of course, only happen if the right circumstances arise. Let us for example look at the following query: @@ -22,30 +22,26 @@ When using A as the left table we ensure that the query will return at least as many rows as there are in that table. For rows where the join condition (B.id = A.id) is not met the selected column (A.colA) will -contain a NULL value. +still contain it's original value. The not seen B.* row would contain all NULL:s. However, the result set could actually contain more rows than what is found in tableA if there are duplicates of the column B.id in tableB. If -A -contains a row [1, "val1"] and B the rows [1, "other1a"],[1, "other1b"] +A contains a row [1, "val1"] and B the rows [1, "other1a"],[1, "other1b"] then two rows will match in the join condition. The only way to know -what -the result will look like is to actually touch both tables during +what the result will look like is to actually touch both tables during execution. Instead, let's say that tableB contains rows that make it possible to place a unique constraint on the column B.id, for example and often the case a primary key. In this situation we know that we will get exactly -as -many rows as there are in tableA, since joining with tableB cannot +as many rows as there are in tableA, since joining with tableB cannot introduce any duplicates. If further, as in the example query, we do not select any columns from tableB, touching that table during execution is -unneccessary. We can remove the whole join operation from the execution +unnecessary. We can remove the whole join operation from the execution plan. Both SQL Server 2005/2008 and Oracle 11g will deploy table elimination -in -the case described above. Let us look at a more advanced query, where +in the case described above. Let us look at a more advanced query, where Oracle fails. select -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Version updated. --- /tmp/wklog.17.old.30176 2009-05-22 17:00:35.000000000 +0300 +++ /tmp/wklog.17.new.30176 2009-05-22 17:00:35.000000000 +0300 @@ -1 +1 @@ -Maria-2.0 +Server-5.1 -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Category updated. --- /tmp/wklog.17.old.30162 2009-05-22 17:00:28.000000000 +0300 +++ /tmp/wklog.17.new.30162 2009-05-22 17:00:28.000000000 +0300 @@ -1 +1 @@ -Maria-Sprint +Server-Sprint -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Version updated. --- /tmp/wklog.17.old.30162 2009-05-22 17:00:28.000000000 +0300 +++ /tmp/wklog.17.new.30162 2009-05-22 17:00:28.000000000 +0300 @@ -1 +1 @@ -2.0 +9.x -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Version updated. --- /tmp/wklog.17.old.30162 2009-05-22 17:00:28.000000000 +0300 +++ /tmp/wklog.17.new.30162 2009-05-22 17:00:28.000000000 +0300 @@ -1 +1 @@ -9.x +Maria-2.0 -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Category updated. --- /tmp/wklog.17.old.30122 2009-05-22 17:00:02.000000000 +0300 +++ /tmp/wklog.17.new.30122 2009-05-22 17:00:02.000000000 +0300 @@ -1 +1 @@ -Server-RawIdeaBin +Maria-Sprint -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Version updated. --- /tmp/wklog.17.old.30122 2009-05-22 17:00:02.000000000 +0300 +++ /tmp/wklog.17.new.30122 2009-05-22 17:00:02.000000000 +0300 @@ -1 +1 @@ -Server-5.2 +2.0 -=-=(Guest - Fri, 22 May 2009, 17:00)=-=- Status updated. --- /tmp/wklog.17.old.30122 2009-05-22 17:00:02.000000000 +0300 +++ /tmp/wklog.17.new.30122 2009-05-22 17:00:02.000000000 +0300 @@ -1 +1 @@ -Un-Assigned +Assigned -=-=(Guest - Thu, 21 May 2009, 22:54)=-=- Low Level Design modified. --- /tmp/wklog.17.old.28468 2009-05-21 22:54:28.000000000 +0300 +++ /tmp/wklog.17.new.28468 2009-05-21 22:54:28.000000000 +0300 @@ -77,7 +77,7 @@ - Relationship with prepared statements. On one hand, it's natural to desire to make table elimination a once-per-statement operation, like outer->inner join conversion. We'll have - to limit the applicablity by removing [MARK1] as that can change during + to limit the applicability by removing [MARK1] as that can change during lifetime of the statement. The other option is to do table elimination every time. This will require to -=-=(Psergey - Tue, 19 May 2009, 20:20)=-=- Low Level Design modified. --- /tmp/wklog.17.old.27126 2009-05-19 20:20:06.000000000 +0300 +++ /tmp/wklog.17.new.27126 2009-05-19 20:20:06.000000000 +0300 @@ -48,6 +48,10 @@ another outer join nest, that shouldn't prevent us from moving away the eliminated tables. +* Update join->table_count and all-join-tables bitmap. + +* That's it. Nothing else? + 4. User interface ----------------- * We'll add an @@optimizer switch flag for table elimination. Tentative ------------------------------------------------------------ -=-=(View All Progress Notes, 13 total)=-=- http://askmonty.org/worklog/index.pl?tid=17&nolimit=1 DESCRIPTION: Eliminate not needed tables from SELECT queries.. This will speed up some views and automatically generated queries. Example: CREATE TABLE B (id int primary key); select A.colA from tableA A left outer join tableB B on B.id = A.id; In this case we can remove table B and the join from the query. HIGH-LEVEL SPECIFICATION: Here is an extended explanation of table elimination. Table elimination is a feature found in some modern query optimizers, of which Microsoft SQL Server 2005/2008 seems to have the most advanced implementation. Oracle 11g has also been confirmed to use table elimination but not to the same extent. Basically, what table elimination does, is to remove tables from the execution plan when it is unnecessary to include them. This can, of course, only happen if the right circumstances arise. Let us for example look at the following query: select A.colA from tableA A left outer join tableB B on B.id = A.id; When using A as the left table we ensure that the query will return at least as many rows as there are in that table. For rows where the join condition (B.id = A.id) is not met the selected column (A.colA) will still contain it's original value. The not seen B.* row would contain all NULL:s. However, the result set could actually contain more rows than what is found in tableA if there are duplicates of the column B.id in tableB. If A contains a row [1, "val1"] and B the rows [1, "other1a"],[1, "other1b"] then two rows will match in the join condition. The only way to know what the result will look like is to actually touch both tables during execution. Instead, let's say that tableB contains rows that make it possible to place a unique constraint on the column B.id, for example and often the case a primary key. In this situation we know that we will get exactly as many rows as there are in tableA, since joining with tableB cannot introduce any duplicates. If further, as in the example query, we do not select any columns from tableB, touching that table during execution is unnecessary. We can remove the whole join operation from the execution plan. Both SQL Server 2005/2008 and Oracle 11g will deploy table elimination in the case described above. Let us look at a more advanced query, where Oracle fails. select A.colA from tableA A left outer join tableB B on B.id = A.id and B.fromDate = ( select max(sub.fromDate) from tableB sub where sub.id = A.id ); In this example we have added another join condition, which ensures that we only pick the matching row from tableB having the latest fromDate. In this case tableB will contain duplicates of the column B.id, so in order to ensure uniqueness the primary key has to contain the fromDate column as well. In other words the primary key of tableB is (B.id, B.fromDate). Furthermore, since the subselect ensures that we only pick the latest B.fromDate for a given B.id we know that at most one row will match the join condition. We will again have the situation where joining with tableB cannot affect the number of rows in the result set. Since we do not select any columns from tableB, the whole join operation can be eliminated from the execution plan. SQL Server 2005/2008 will deploy table elimination in this situation as well. We have not found a way to make Oracle 11g use it for this type of query. Queries like these arise in two situations. Either when you have denormalized model consisting of a fact table with several related dimension tables, or when you have a highly normalized model where each attribute is stored in its own table. The example with the subselect is common whenever you store historized/versioned data. LOW-LEVEL DESIGN: <contents> 1. Conditions for removal 2. Removal operation properties 3. Removal operation 4. User interface 5. Todo, issues to resolve 5.1 To resolve 5.2 Resolved </contents> It's not really about elimination of tables, it's about elimination of inner sides of outer joins. 1. Conditions for removal ------------------------- We can eliminate an inner side of outer join if: 1. For each record combination of outer tables, it will always produce exactly one record. 2. There are no references to columns of the inner tables anywhere else in the query. #1 means that every table inside the outer join nest is: - is a constant table: = because it can be accessed via eq_ref(const) access, or = it is a zero-rows or one-row MyISAM-like table [MARK1] - has an eq_ref access method candidate. #2 means that WHERE clause, ON clauses of embedding outer joins, ORDER BY, GROUP BY and HAVING do not refer to the inner tables of the outer join nest. 2. Removal operation properties ------------------------------- * There is always one way to remove (no choice to remove either this or that) * It is always better to remove as much tables as possible (at least within our cost model). Thus, no need for any cost calculations/etc. It's an unconditional rewrite. 3. Removal operation -------------------- * Remove the outer join nest's nested join structure (i.e. get the outer join's TABLE_LIST object $OJ and remove it from $OJ->embedding, $OJ->embedding->nested_join. Update table_map's of all ancestor nested joins). [MARK2] * Move the tables and their JOIN_TABs to front like it is done with const tables, with exception that if eliminated outer join nest was within another outer join nest, that shouldn't prevent us from moving away the eliminated tables. * Update join->table_count and all-join-tables bitmap. * That's it. Nothing else? 4. User interface ----------------- * We'll add an @@optimizer switch flag for table elimination. Tentative name: 'table_elimination'. * With EXPLAIN, there are two options: - Show removed tables in a way similar to const tables, with some indication that they are removed. - Do not show them altogether. (the second one seems to be better? We're targeting a situation with VIEWs, where the user would not care about what tables were added into his query and then discarded from it?) 5. Todo, issues to resolve -------------------------- 5.1 To resolve ~~~~~~~~~~~~~~ - See EXPLAIN question in section #4. - Re-check how this works with equality propagation. - Relationship with prepared statements. On one hand, it's natural to desire to make table elimination a once-per-statement operation, like outer->inner join conversion. We'll have to limit the applicability by removing [MARK1] as that can change during lifetime of the statement. The other option is to do table elimination every time. This will require to rework operation [MARK2] to be undoable. I'm leaning towards doing the former. With anchor modeling, it is unlikely that we'll meet outer joins which have N inner tables of which some are 1-row MyISAM tables that do not have primary key. 5.2 Resolved ~~~~~~~~~~~~ - outer->inner join conversion is not a problem for table elimination. We make outer->inner conversions based on predicates in WHERE. If the WHERE referred to an inner table (requirement for OJ->IJ conversion) then table elimination would not be applicable anyway. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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