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pgstat: Prepare to use mechanism for truncated rels also for droppped rels.

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The upcoming shared memory stats patch drops stats for dropped objects in a
transactional manner, rather than removing them later as part of vacuum. This
means that stats for DROP inside a transaction needs to handle aborted
(sub-)transactions similar to TRUNCATE: The stats up to the DROP should be
restored.

Rename the existing infrastructure in preparation.

Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210405092914.mmxqe7j56lsjfsej@alap3.anarazel.de
This commit is contained in:
Andres Freund 2021-04-03 17:39:54 -07:00
parent e1f958d759
commit 6b9501660c
2 changed files with 57 additions and 48 deletions
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93
src/backend/postmaster/pgstat.c
View File

@ -257,12 +257,13 @@ typedef struct TwoPhasePgStatRecord
PgStat_Counter tuples_inserted; /* tuples inserted in xact */
PgStat_Counter tuples_updated; /* tuples updated in xact */
PgStat_Counter tuples_deleted; /* tuples deleted in xact */
PgStat_Counter inserted_pre_trunc; /* tuples inserted prior to truncate */
PgStat_Counter updated_pre_trunc; /* tuples updated prior to truncate */
PgStat_Counter deleted_pre_trunc; /* tuples deleted prior to truncate */
/* tuples i/u/d prior to truncate/drop */
PgStat_Counter inserted_pre_truncdrop;
PgStat_Counter updated_pre_truncdrop;
PgStat_Counter deleted_pre_truncdrop;
Oid t_id; /* table's OID */
bool t_shared; /* is it a shared catalog? */
bool t_truncated; /* was the relation truncated? */
bool t_truncdropped; /* was the relation truncated/dropped? */
} TwoPhasePgStatRecord;
/*
@ -2300,36 +2301,39 @@ pgstat_count_heap_delete(Relation rel)
}
/*
* pgstat_truncate_save_counters
* pgstat_truncdrop_save_counters
*
* Whenever a table is truncated, we save its i/u/d counters so that they can
* be cleared, and if the (sub)xact that executed the truncate later aborts,
* the counters can be restored to the saved (pre-truncate) values. Note we do
* this on the first truncate in any particular subxact level only.
* Whenever a table is truncated/dropped, we save its i/u/d counters so that
* they can be cleared, and if the (sub)xact that executed the truncate/drop
* later aborts, the counters can be restored to the saved (pre-truncate/drop)
* values.
*
* Note that for truncate we do this on the first truncate in any particular
* subxact level only.
*/
static void
pgstat_truncate_save_counters(PgStat_TableXactStatus *trans)
pgstat_truncdrop_save_counters(PgStat_TableXactStatus *trans, bool is_drop)
{
if (!trans->truncated)
if (!trans->truncdropped || is_drop)
{
trans->inserted_pre_trunc = trans->tuples_inserted;
trans->updated_pre_trunc = trans->tuples_updated;
trans->deleted_pre_trunc = trans->tuples_deleted;
trans->truncated = true;
trans->inserted_pre_truncdrop = trans->tuples_inserted;
trans->updated_pre_truncdrop = trans->tuples_updated;
trans->deleted_pre_truncdrop = trans->tuples_deleted;
trans->truncdropped = true;
}
}
/*
* pgstat_truncate_restore_counters - restore counters when a truncate aborts
* pgstat_truncdrop_restore_counters - restore counters when a truncate aborts
*/
static void
pgstat_truncate_restore_counters(PgStat_TableXactStatus *trans)
pgstat_truncdrop_restore_counters(PgStat_TableXactStatus *trans)
{
if (trans->truncated)
if (trans->truncdropped)
{
trans->tuples_inserted = trans->inserted_pre_trunc;
trans->tuples_updated = trans->updated_pre_trunc;
trans->tuples_deleted = trans->deleted_pre_trunc;
trans->tuples_inserted = trans->inserted_pre_truncdrop;
trans->tuples_updated = trans->updated_pre_truncdrop;
trans->tuples_deleted = trans->deleted_pre_truncdrop;
}
}
@ -2350,7 +2354,7 @@ pgstat_count_truncate(Relation rel)
pgstat_info->trans->nest_level != nest_level)
add_tabstat_xact_level(pgstat_info, nest_level);
pgstat_truncate_save_counters(pgstat_info->trans);
pgstat_truncdrop_save_counters(pgstat_info->trans, false);
pgstat_info->trans->tuples_inserted = 0;
pgstat_info->trans->tuples_updated = 0;
pgstat_info->trans->tuples_deleted = 0;
@ -2395,17 +2399,17 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit)
Assert(trans->upper == NULL);
tabstat = trans->parent;
Assert(tabstat->trans == trans);
/* restore pre-truncate stats (if any) in case of aborted xact */
/* restore pre-truncate/drop stats (if any) in case of aborted xact */
if (!isCommit)
pgstat_truncate_restore_counters(trans);
pgstat_truncdrop_restore_counters(trans);
/* count attempted actions regardless of commit/abort */
tabstat->t_counts.t_tuples_inserted += trans->tuples_inserted;
tabstat->t_counts.t_tuples_updated += trans->tuples_updated;
tabstat->t_counts.t_tuples_deleted += trans->tuples_deleted;
if (isCommit)
{
tabstat->t_counts.t_truncated = trans->truncated;
if (trans->truncated)
tabstat->t_counts.t_truncdropped = trans->truncdropped;
if (trans->truncdropped)
{
/* forget live/dead stats seen by backend thus far */
tabstat->t_counts.t_delta_live_tuples = 0;
@ -2504,10 +2508,10 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in
{
if (trans->upper && trans->upper->nest_level == nestDepth - 1)
{
if (trans->truncated)
if (trans->truncdropped)
{
/* propagate the truncate status one level up */
pgstat_truncate_save_counters(trans->upper);
/* propagate the truncate/drop status one level up */
pgstat_truncdrop_save_counters(trans->upper, false);
/* replace upper xact stats with ours */
trans->upper->tuples_inserted = trans->tuples_inserted;
trans->upper->tuples_updated = trans->tuples_updated;
@ -2547,8 +2551,8 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in
* subtransaction
*/
/* first restore values obliterated by truncate */
pgstat_truncate_restore_counters(trans);
/* first restore values obliterated by truncate/drop */
pgstat_truncdrop_restore_counters(trans);
/* count attempted actions regardless of commit/abort */
tabstat->t_counts.t_tuples_inserted += trans->tuples_inserted;
tabstat->t_counts.t_tuples_updated += trans->tuples_updated;
@ -2609,12 +2613,12 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
record.tuples_inserted = trans->tuples_inserted;
record.tuples_updated = trans->tuples_updated;
record.tuples_deleted = trans->tuples_deleted;
record.inserted_pre_trunc = trans->inserted_pre_trunc;
record.updated_pre_trunc = trans->updated_pre_trunc;
record.deleted_pre_trunc = trans->deleted_pre_trunc;
record.inserted_pre_truncdrop = trans->inserted_pre_truncdrop;
record.updated_pre_truncdrop = trans->updated_pre_truncdrop;
record.deleted_pre_truncdrop = trans->deleted_pre_truncdrop;
record.t_id = tabstat->t_id;
record.t_shared = tabstat->t_shared;
record.t_truncated = trans->truncated;
record.t_truncdropped = trans->truncdropped;
RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
&record, sizeof(TwoPhasePgStatRecord));
@ -2710,8 +2714,8 @@ pgstat_twophase_postcommit(TransactionId xid, uint16 info,
pgstat_info->t_counts.t_tuples_inserted += rec->tuples_inserted;
pgstat_info->t_counts.t_tuples_updated += rec->tuples_updated;
pgstat_info->t_counts.t_tuples_deleted += rec->tuples_deleted;
pgstat_info->t_counts.t_truncated = rec->t_truncated;
if (rec->t_truncated)
pgstat_info->t_counts.t_truncdropped = rec->t_truncdropped;
if (rec->t_truncdropped)
{
/* forget live/dead stats seen by backend thus far */
pgstat_info->t_counts.t_delta_live_tuples = 0;
@ -2743,11 +2747,11 @@ pgstat_twophase_postabort(TransactionId xid, uint16 info,
pgstat_info = get_tabstat_entry(rec->t_id, rec->t_shared);
/* Same math as in AtEOXact_PgStat, abort case */
if (rec->t_truncated)
if (rec->t_truncdropped)
{
rec->tuples_inserted = rec->inserted_pre_trunc;
rec->tuples_updated = rec->updated_pre_trunc;
rec->tuples_deleted = rec->deleted_pre_trunc;
rec->tuples_inserted = rec->inserted_pre_truncdrop;
rec->tuples_updated = rec->updated_pre_truncdrop;
rec->tuples_deleted = rec->deleted_pre_truncdrop;
}
pgstat_info->t_counts.t_tuples_inserted += rec->tuples_inserted;
pgstat_info->t_counts.t_tuples_updated += rec->tuples_updated;
@ -5055,8 +5059,11 @@ pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len)
tabentry->tuples_updated += tabmsg->t_counts.t_tuples_updated;
tabentry->tuples_deleted += tabmsg->t_counts.t_tuples_deleted;
tabentry->tuples_hot_updated += tabmsg->t_counts.t_tuples_hot_updated;
/* If table was truncated, first reset the live/dead counters */
if (tabmsg->t_counts.t_truncated)
/*
* If table was truncated/dropped, first reset the live/dead
* counters.
*/
if (tabmsg->t_counts.t_truncdropped)
{
tabentry->n_live_tuples = 0;
tabentry->n_dead_tuples = 0;

12
src/include/pgstat.h
View File

@ -123,7 +123,7 @@ typedef struct PgStat_TableCounts
PgStat_Counter t_tuples_updated;
PgStat_Counter t_tuples_deleted;
PgStat_Counter t_tuples_hot_updated;
bool t_truncated;
bool t_truncdropped;
PgStat_Counter t_delta_live_tuples;
PgStat_Counter t_delta_dead_tuples;
@ -186,10 +186,12 @@ typedef struct PgStat_TableXactStatus
PgStat_Counter tuples_inserted; /* tuples inserted in (sub)xact */
PgStat_Counter tuples_updated; /* tuples updated in (sub)xact */
PgStat_Counter tuples_deleted; /* tuples deleted in (sub)xact */
bool truncated; /* relation truncated in this (sub)xact */
PgStat_Counter inserted_pre_trunc; /* tuples inserted prior to truncate */
PgStat_Counter updated_pre_trunc; /* tuples updated prior to truncate */
PgStat_Counter deleted_pre_trunc; /* tuples deleted prior to truncate */
bool truncdropped; /* relation truncated/dropped in this
* (sub)xact */
/* tuples i/u/d prior to truncate/drop */
PgStat_Counter inserted_pre_truncdrop;
PgStat_Counter updated_pre_truncdrop;
PgStat_Counter deleted_pre_truncdrop;
int nest_level; /* subtransaction nest level */
/* links to other structs for same relation: */
struct PgStat_TableXactStatus *upper; /* next higher subxact if any */