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Remove redundant gettimeofday() calls to the extent practical without

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changing semantics too much.  statement_timestamp is now set immediately
upon receipt of a client command message, and the various places that used
to do their own gettimeofday() calls to mark command startup are referenced
to that instead.  I have also made stats_command_string use that same
value for pg_stat_activity.query_start for both the command itself and
its eventual replacement by <IDLE> or <idle in transaction>.  There was
some debate about that, but no argument that seemed convincing enough to
justify an extra gettimeofday() call.
This commit is contained in:
Tom Lane
2006-06-20 22:52:00 +00:00
parent 47a37aeebd
commit 27c3e3de09
11 changed files with 269 additions and 226 deletions
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13
src/backend/access/transam/xact.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.220 2006/04/25 00:25:17 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.221 2006/06/20 22:51:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -167,9 +167,10 @@ static SubTransactionId currentSubTransactionId;
static CommandId currentCommandId;
/*
* This is the value of now(), ie, the transaction start time.
* This does not change as we enter and exit subtransactions, so we don't
* keep it inside the TransactionState stack.
* xactStartTimestamp is the value of transaction_timestamp().
* stmtStartTimestamp is the value of statement_timestamp().
* These do not change as we enter and exit subtransactions, so we don't
* keep them inside the TransactionState stack.
*/
static TimestampTz xactStartTimestamp;
static TimestampTz stmtStartTimestamp;
@ -1386,7 +1387,9 @@ StartTransaction(void)
XactLockTableInsert(s->transactionId);
/*
* now() and statement_timestamp() should be the same time
* set transaction_timestamp() (a/k/a now()). We want this to be the
* same as the first command's statement_timestamp(), so don't do a
* fresh GetCurrentTimestamp() call (which'd be expensive anyway).
*/
xactStartTimestamp = stmtStartTimestamp;