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Just-in-time background writing strategy. This code avoids re-scanning

buffers that cannot possibly need to be cleaned, and estimates how many
buffers it should try to clean based on moving averages of recent allocation
requests and density of reusable buffers.  The patch also adds a couple
more columns to pg_stat_bgwriter to help measure the effectiveness of the
bgwriter.

Greg Smith, building on his own work and ideas from several other people,
in particular a much older patch from Itagaki Takahiro.
This commit is contained in:
Tom Lane
2007-09-25 20:03:38 +00:00
parent 588901df84
commit 6f5c38dcd0
16 changed files with 447 additions and 105 deletions

View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.45 2007/09/20 17:56:31 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.46 2007/09/25 20:03:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -67,6 +67,8 @@ extern Datum pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_buf_alloc(PG_FUNCTION_ARGS);
extern Datum pg_stat_clear_snapshot(PG_FUNCTION_ARGS);
extern Datum pg_stat_reset(PG_FUNCTION_ARGS);
@ -813,6 +815,18 @@ pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS)
PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_clean);
}
Datum
pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_backend);
}
Datum
pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_alloc);
}
/* Discard the active statistics snapshot */
Datum