----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Implement Block Nested Loop Hash Join CREATION DATE..: Wed, 04 Aug 2010, 18:56 SUPERVISOR.....: Monty IMPLEMENTOR....: Igor COPIES TO......: Igor Mneptok Monty Psergey Sanja Sergei Timour CATEGORY.......: Server-BackLog TASK ID........: 128 (http://askmonty.org/worklog/?tid=128) VERSION........: Server-5.3 STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: DESCRIPTION: Block Nested Loop Hash (BNLH) Join Algorithm (also known as Classic Hash Join Algorithm) can be applied when the join condition contains conjunctive equality predicates over some attributes of the joined tables. The algorithm employs the same logical schema as Block Nested Loop Join Algorithm. A portions of rows of the left join operand fit into a preallocated join buffer are put into the buffer. A hash table over the equi-join attributes for the rows in the buffer is built. Then the table of the second operand is scanned and for each row from this table the matching rows in the join buffer are found using the built hash table. These actions are repeated until there is no more rows can be supplied by the first operand. The algorithm requires as many scans of the second table as many times the join buffer is refilled. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v4.0.0)