database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-07 00:36:50 +03:00
Code Activity

Prevent WAL logging when COPY is done in the same transation that

Browse Source 
created it.

Simon Riggs
This commit is contained in:
Bruce Momjian
2007-01-25 02:17:26 +00:00
parent 693c85d954
commit ef65f6f7a4
10 changed files with 182 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
src/backend/commands/copy.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.274 2007/01/05 22:19:25 momjian Exp $
* $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.275 2007/01/25 02:17:26 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -1652,6 +1652,7 @@ CopyFrom(CopyState cstate)
ExprContext *econtext; /* used for ExecEvalExpr for default atts */
MemoryContext oldcontext = CurrentMemoryContext;
ErrorContextCallback errcontext;
bool use_wal = true; /* By default, we use WAL to log db changes */
Assert(cstate->rel);
@ -1843,6 +1844,28 @@ CopyFrom(CopyState cstate)
nfields = file_has_oids ? (attr_count + 1) : attr_count;
field_strings = (char **) palloc(nfields * sizeof(char *));
/*
* Check for performance optimization by avoiding WAL writes
*
* If archive logging is not be enabled *and* either
* - table is created in same transaction as this COPY
* - table data is now being written to new relfilenode
* then we can safely avoid writing WAL. Why?
* The data files for the table plus toast table/index, plus any indexes
* will all be dropped at the end of the transaction if it fails, so we
* do not need to worry about inconsistent states.
* As mentioned in comments in utils/rel.h, the in-same-transaction test is
* not completely reliable, since rd_createSubId can be reset to zero in
* certain cases before the end of the creating transaction.
* We are doing this for performance only, so we only need to know:
* if rd_createSubid != InvalidSubTransactionId then it is *always* just
* created. If we have PITR enabled, then we *must* use_wal
*/
if ((cstate->rel->rd_createSubid != InvalidSubTransactionId ||
cstate->rel->rd_newRelfilenodeSubid != InvalidSubTransactionId)
&& !XLogArchivingActive())
use_wal = false;
/* Initialize state variables */
cstate->fe_eof = false;
cstate->eol_type = EOL_UNKNOWN;
@ -2076,7 +2099,7 @@ CopyFrom(CopyState cstate)
ExecConstraints(resultRelInfo, slot, estate);
/* OK, store the tuple and create index entries for it */
simple_heap_insert(cstate->rel, tuple);
fast_heap_insert(cstate->rel, tuple, use_wal);
if (resultRelInfo->ri_NumIndices > 0)
ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
@ -2093,6 +2116,32 @@ CopyFrom(CopyState cstate)
}
}
/*
* If we skipped writing WAL for heaps, then we need to sync
*/
if (!use_wal)
{
/* main heap */
heap_sync(cstate->rel);
/* main heap indexes, if any */
/* we always use WAL for index inserts, so no need to sync */
/* toast heap, if any */
if (OidIsValid(cstate->rel->rd_rel->reltoastrelid))
{
Relation toastrel;
toastrel = heap_open(cstate->rel->rd_rel->reltoastrelid,
AccessShareLock);
heap_sync(toastrel);
heap_close(toastrel, AccessShareLock);
}
/* toast index, if toast heap */
/* we always use WAL for index inserts, so no need to sync */
}
/* Done, clean up */
error_context_stack = errcontext.previous;