NotificationsYou must be signed in to change notification settings
Fork6
Star31

Commit4075fc4

committed

Further twiddling of nodeHash.c hashtable sizing calculation.

On reflection, the submitted patch didn't really work to prevent therequest size from exceeding MaxAllocSize, because of the fact that we'dhappily round nbuckets up to the next power of 2 after we'd limited it tomax_pointers. The simplest way to enforce the limit correctly is toround max_pointers down to a power of 2 when it isn't one already.(Note that the constraint to INT_MAX / 2, if it were doing anything usefulat all, is properly applied after that.)

1 parentff4cbc1 commit4075fc4Copy full SHA for 4075fc4

File tree

1 file changed

-1

lines changed

src/backend/executor
- nodeHash.c

1 file changed

-1

lines changed

`‎src/backend/executor/nodeHash.c`

Lines changed: 7 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -397,6 +397,7 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,`
`397`	`397`	`longhash_table_bytes;`
`398`	`398`	`longskew_table_bytes;`
`399`	`399`	`longmax_pointers;`
	`400`	`+longmppow2;`
`400`	`401`	`intnbatch;`
`401`	`402`	`intnbuckets;`
`402`	`403`	`inti;`
`@@ -464,7 +465,12 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,`
`464`	`465`	`*/`
`465`	`466`	`max_pointers= (work_mem*1024L) /sizeof(HashJoinTuple);`
`466`	`467`	`max_pointers=Min(max_pointers,MaxAllocSize /sizeof(HashJoinTuple));`
`467`		`-/* also ensure we avoid integer overflow in nbatch and nbuckets */`
	`468`	`+/* If max_pointers isn't a power of 2, must round it down to one */`
	`469`	`+mppow2=1L <<my_log2(max_pointers);`
	`470`	`+if (max_pointers!=mppow2)`
	`471`	`+max_pointers=mppow2 /2;`
	`472`	`+`
	`473`	`+/* Also ensure we avoid integer overflow in nbatch and nbuckets */`
`468`	`474`	`/* (this step is redundant given the current value of MaxAllocSize) */`
`469`	`475`	`max_pointers=Min(max_pointers,INT_MAX /2);`
`470`	`476`

0 commit comments

Comments

(0)

Movatterモバイル変換

Navigation Menu

Search code, repositories, users, issues, pull requests...

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Commit4075fc4

File tree

1 file changed

1 file changed

`‎src/backend/executor/nodeHash.c`

0 commit comments