----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Add a mysqlbinlog option to filter updates to certain tables CREATION DATE..: Mon, 10 Aug 2009, 13:25 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Psergey CATEGORY.......: Server-RawIdeaBin TASK ID........: 40 (http://askmonty.org/worklog/?tid=40) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Knielsen - Fri, 14 Aug 2009, 15:47)=-=- High-Level Specification modified. --- /tmp/wklog.40.old.10896 2009-08-14 15:47:39.000000000 +0300 +++ /tmp/wklog.40.new.10896 2009-08-14 15:47:39.000000000 +0300 @@ -72,3 +72,21 @@ /* !mysqlbinlog: updates t1,db3.t2 */ UPDATE t1 LEFT JOIN ... and further processing in mysqlbinlog will be trivial. + +2.4 Implement server functionality to ignore certain tables +----------------------------------------------------------- + +We could add a general facility in the server to ignore certain tables: + + SET SESSION ignored_tables = "db1.t1,db2.t2"; + +This would work similar to --replicate-ignore-table, but in a general way not +restricted to the slave SQL thread. + +It would then be trivial for mysqlbinlog to add such statements at the start +of the output, or probably the user could just do it manually with no need for +additional options for mysqlbinlog. + +It might be useful to integrate this with the code that already handles +--replicate-ignore-db and similar slave options. + -=-=(Psergey - Mon, 10 Aug 2009, 15:41)=-=- High-Level Specification modified. --- /tmp/wklog.40.old.12989 2009-08-10 15:41:23.000000000 +0300 +++ /tmp/wklog.40.new.12989 2009-08-10 15:41:23.000000000 +0300 @@ -1,6 +1,7 @@ - 1. Context ---------- +(See http://askmonty.org/wiki/index.php/Scratch/ReplicationOptions for global +overview) At the moment, the server has these replication slave options: --replicate-do-table=db.tbl -=-=(Guest - Mon, 10 Aug 2009, 14:52)=-=- Dependency created: 39 now depends on 40 -=-=(Guest - Mon, 10 Aug 2009, 14:51)=-=- High Level Description modified. --- /tmp/wklog.40.old.16985 2009-08-10 14:51:59.000000000 +0300 +++ /tmp/wklog.40.new.16985 2009-08-10 14:51:59.000000000 +0300 @@ -1,3 +1,4 @@ Replication slave can be set to filter updates to certain tables with ---replicate-[wild-]{do,ignore}-table options. This task is about adding similar -functionality to mysqlbinlog. +--replicate-[wild-]{do,ignore}-table options. + +This task is about adding similar functionality to mysqlbinlog. -=-=(Guest - Mon, 10 Aug 2009, 14:51)=-=- High-Level Specification modified. --- /tmp/wklog.40.old.16949 2009-08-10 14:51:33.000000000 +0300 +++ /tmp/wklog.40.new.16949 2009-08-10 14:51:33.000000000 +0300 @@ -1 +1,73 @@ +1. Context +---------- +At the moment, the server has these replication slave options: + + --replicate-do-table=db.tbl + --replicate-ignore-table=db.tbl + --replicate-wild-do-table=pattern.pattern + --replicate-wild-ignore-table=pattern.pattern + +They affect both RBR and SBR events. SBR events are checked after the +statement has been parsed, the server iterates over list of used tables and +checks them againist --replicate instructions. + +What is interesting is that this scheme still allows to update the ignored +table through a VIEW. + +2. Table filtering in mysqlbinlog +--------------------------------- + +Per-table filtering of RBR events is easy (as it is relatively easy to extract +the name of the table that the event applies to). + +Per-table filtering of SBR events is hard, as generally it is not apparent +which tables the statement refers to. + +This opens possible options: + +2.1 Put the parser into mysqlbinlog +----------------------------------- +Once we have a full parser in mysqlbinlog, we'll be able to check which tables +are used by a statement, and will allow to show behaviour identical to those +that one obtains when using --replicate-* slave options. + +(It is not clear how much effort is needed to put the parser into mysqlbinlog. +Any guesses?) + + +2.2 Use dumb regexp match +------------------------- +Use a really dumb approach. A query is considered to be modifying table X if +it matches an expression + +CREATE TABLE $tablename +DROP $tablename +UPDATE ...$tablename ... SET // here '...' can't contain the word 'SET' +DELETE ...$tablename ... WHERE // same as above +ALTER TABLE $tablename +.. etc (go get from the grammar) .. + +The advantage over doing the same in awk is that mysqlbinlog will also process +RBR statements, and together with that will provide a working solution for +those who are careful with their table names not mixing with string constants +and such. + +(TODO: string constants are of particular concern as they come from +[potentially hostile] users, unlike e.g. table aliases which come from +[not hostile] developers. Remove also all string constants before attempting +to do match?) + +2.3 Have the master put annotations +----------------------------------- +We could add a master option so that it injects into query a mark that tells +which tables the query will affect, e.g. for the query + + UPDATE t1 LEFT JOIN db3.t2 ON ... WHERE ... + + +the binlog will have + + /* !mysqlbinlog: updates t1,db3.t2 */ UPDATE t1 LEFT JOIN ... + +and further processing in mysqlbinlog will be trivial. DESCRIPTION: Replication slave can be set to filter updates to certain tables with --replicate-[wild-]{do,ignore}-table options. This task is about adding similar functionality to mysqlbinlog. HIGH-LEVEL SPECIFICATION: 1. Context ---------- (See http://askmonty.org/wiki/index.php/Scratch/ReplicationOptions for global overview) At the moment, the server has these replication slave options: --replicate-do-table=db.tbl --replicate-ignore-table=db.tbl --replicate-wild-do-table=pattern.pattern --replicate-wild-ignore-table=pattern.pattern They affect both RBR and SBR events. SBR events are checked after the statement has been parsed, the server iterates over list of used tables and checks them againist --replicate instructions. What is interesting is that this scheme still allows to update the ignored table through a VIEW. 2. Table filtering in mysqlbinlog --------------------------------- Per-table filtering of RBR events is easy (as it is relatively easy to extract the name of the table that the event applies to). Per-table filtering of SBR events is hard, as generally it is not apparent which tables the statement refers to. This opens possible options: 2.1 Put the parser into mysqlbinlog ----------------------------------- Once we have a full parser in mysqlbinlog, we'll be able to check which tables are used by a statement, and will allow to show behaviour identical to those that one obtains when using --replicate-* slave options. (It is not clear how much effort is needed to put the parser into mysqlbinlog. Any guesses?) 2.2 Use dumb regexp match ------------------------- Use a really dumb approach. A query is considered to be modifying table X if it matches an expression CREATE TABLE $tablename DROP $tablename UPDATE ...$tablename ... SET // here '...' can't contain the word 'SET' DELETE ...$tablename ... WHERE // same as above ALTER TABLE $tablename .. etc (go get from the grammar) .. The advantage over doing the same in awk is that mysqlbinlog will also process RBR statements, and together with that will provide a working solution for those who are careful with their table names not mixing with string constants and such. (TODO: string constants are of particular concern as they come from [potentially hostile] users, unlike e.g. table aliases which come from [not hostile] developers. Remove also all string constants before attempting to do match?) 2.3 Have the master put annotations ----------------------------------- We could add a master option so that it injects into query a mark that tells which tables the query will affect, e.g. for the query UPDATE t1 LEFT JOIN db3.t2 ON ... WHERE ... the binlog will have /* !mysqlbinlog: updates t1,db3.t2 */ UPDATE t1 LEFT JOIN ... and further processing in mysqlbinlog will be trivial. 2.4 Implement server functionality to ignore certain tables ----------------------------------------------------------- We could add a general facility in the server to ignore certain tables: SET SESSION ignored_tables = "db1.t1,db2.t2"; This would work similar to --replicate-ignore-table, but in a general way not restricted to the slave SQL thread. It would then be trivial for mysqlbinlog to add such statements at the start of the output, or probably the user could just do it manually with no need for additional options for mysqlbinlog. It might be useful to integrate this with the code that already handles --replicate-ignore-db and similar slave options. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)