Do not use in-place updates for statistics import.

The use of in-place updates was originally there to follow the
precedent of ANALYZE and to reduce the potential for bloat on
pg_class. Per discussion, it's not worth the risks.

Reported-by: Andres Freund <[email protected]>
Discussion: https://postgr.es/m/cpdanvzykcb5o64rmapkx6n5gjypoce3y52hff7ocxupgpbxu4@53jmlyvukijo

diff --git a/src/backend/statistics/relation_stats.c b/src/backend/statistics/relation_stats.c
index 1f6c5c39121c9d761669eb7fd8d53f607ac077ed..66731290a3e6beb226758489a44c4362f048d9be 100644 (file)
--- a/src/backend/statistics/relation_stats.c
+++ b/src/backend/statistics/relation_stats.c
@@ -48,14 +48,13 @@ static struct StatsArgInfo relarginfo[] =
    [NUM_RELATION_STATS_ARGS] = {0}
 };
 
-static bool relation_statistics_update(FunctionCallInfo fcinfo, int elevel,
-                                      bool inplace);
+static bool relation_statistics_update(FunctionCallInfo fcinfo, int elevel);
 
 /*
  * Internal function for modifying statistics for a relation.
  */
 static bool
-relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
+relation_statistics_update(FunctionCallInfo fcinfo, int elevel)
 {
    bool        result = true;
    Oid         reloid;
@@ -66,6 +65,12 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
    bool        update_reltuples = false;
    BlockNumber relallvisible = 0;
    bool        update_relallvisible = false;
+   HeapTuple   ctup;
+   Form_pg_class pgcform;
+   int         replaces[3] = {0};
+   Datum       values[3] = {0};
+   bool        nulls[3] = {0};
+   int         nreplaces = 0;
 
    if (!PG_ARGISNULL(RELPAGES_ARG))
    {
@@ -110,101 +115,52 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
     */
    crel = table_open(RelationRelationId, RowExclusiveLock);
 
-   if (inplace)
+   ctup = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
+   if (!HeapTupleIsValid(ctup))
    {
-       HeapTuple   ctup = NULL;
-       ScanKeyData key[1];
-       Form_pg_class pgcform;
-       void       *inplace_state = NULL;
-       bool        dirty = false;
-
-       ScanKeyInit(&key[0], Anum_pg_class_oid, BTEqualStrategyNumber, F_OIDEQ,
-                   ObjectIdGetDatum(reloid));
-       systable_inplace_update_begin(crel, ClassOidIndexId, true, NULL, 1, key,
-                                     &ctup, &inplace_state);
-       if (!HeapTupleIsValid(ctup))
-           elog(ERROR, "pg_class entry for relid %u vanished while updating statistics",
-                reloid);
-       pgcform = (Form_pg_class) GETSTRUCT(ctup);
-
-       if (update_relpages && pgcform->relpages != relpages)
-       {
-           pgcform->relpages = relpages;
-           dirty = true;
-       }
-       if (update_reltuples && pgcform->reltuples != reltuples)
-       {
-           pgcform->reltuples = reltuples;
-           dirty = true;
-       }
-       if (update_relallvisible && pgcform->relallvisible != relallvisible)
-       {
-           pgcform->relallvisible = relallvisible;
-           dirty = true;
-       }
-
-       if (dirty)
-           systable_inplace_update_finish(inplace_state, ctup);
-       else
-           systable_inplace_update_cancel(inplace_state);
-
-       heap_freetuple(ctup);
+       ereport(elevel,
+               (errcode(ERRCODE_OBJECT_IN_USE),
+                errmsg("pg_class entry for relid %u not found", reloid)));
+       table_close(crel, RowExclusiveLock);
+       return false;
    }
-   else
-   {
-       TupleDesc   tupdesc = RelationGetDescr(crel);
-       HeapTuple   ctup;
-       Form_pg_class pgcform;
-       int         replaces[3] = {0};
-       Datum       values[3] = {0};
-       bool        nulls[3] = {0};
-       int         nreplaces = 0;
-
-       ctup = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
-       if (!HeapTupleIsValid(ctup))
-       {
-           ereport(elevel,
-                   (errcode(ERRCODE_OBJECT_IN_USE),
-                    errmsg("pg_class entry for relid %u not found", reloid)));
-           table_close(crel, RowExclusiveLock);
-           return false;
-       }
-       pgcform = (Form_pg_class) GETSTRUCT(ctup);
 
-       if (update_relpages && relpages != pgcform->relpages)
-       {
-           replaces[nreplaces] = Anum_pg_class_relpages;
-           values[nreplaces] = UInt32GetDatum(relpages);
-           nreplaces++;
-       }
+   pgcform = (Form_pg_class) GETSTRUCT(ctup);
 
-       if (update_reltuples && reltuples != pgcform->reltuples)
-       {
-           replaces[nreplaces] = Anum_pg_class_reltuples;
-           values[nreplaces] = Float4GetDatum(reltuples);
-           nreplaces++;
-       }
+   if (update_relpages && relpages != pgcform->relpages)
+   {
+       replaces[nreplaces] = Anum_pg_class_relpages;
+       values[nreplaces] = UInt32GetDatum(relpages);
+       nreplaces++;
+   }
 
-       if (update_relallvisible && relallvisible != pgcform->relallvisible)
-       {
-           replaces[nreplaces] = Anum_pg_class_relallvisible;
-           values[nreplaces] = UInt32GetDatum(relallvisible);
-           nreplaces++;
-       }
+   if (update_reltuples && reltuples != pgcform->reltuples)
+   {
+       replaces[nreplaces] = Anum_pg_class_reltuples;
+       values[nreplaces] = Float4GetDatum(reltuples);
+       nreplaces++;
+   }
 
-       if (nreplaces > 0)
-       {
-           HeapTuple   newtup;
+   if (update_relallvisible && relallvisible != pgcform->relallvisible)
+   {
+       replaces[nreplaces] = Anum_pg_class_relallvisible;
+       values[nreplaces] = UInt32GetDatum(relallvisible);
+       nreplaces++;
+   }
 
-           newtup = heap_modify_tuple_by_cols(ctup, tupdesc, nreplaces,
-                                              replaces, values, nulls);
-           CatalogTupleUpdate(crel, &newtup->t_self, newtup);
-           heap_freetuple(newtup);
-       }
+   if (nreplaces > 0)
+   {
+       TupleDesc   tupdesc = RelationGetDescr(crel);
+       HeapTuple   newtup;
 
-       ReleaseSysCache(ctup);
+       newtup = heap_modify_tuple_by_cols(ctup, tupdesc, nreplaces,
+                                          replaces, values, nulls);
+       CatalogTupleUpdate(crel, &newtup->t_self, newtup);
+       heap_freetuple(newtup);
    }
 
+   ReleaseSysCache(ctup);
+
    /* release the lock, consistent with vac_update_relstats() */
    table_close(crel, RowExclusiveLock);
 
@@ -219,7 +175,7 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
 Datum
 pg_set_relation_stats(PG_FUNCTION_ARGS)
 {
-   relation_statistics_update(fcinfo, ERROR, false);
+   relation_statistics_update(fcinfo, ERROR);
    PG_RETURN_VOID();
 }
 
@@ -243,7 +199,7 @@ pg_clear_relation_stats(PG_FUNCTION_ARGS)
    newfcinfo->args[3].value = UInt32GetDatum(0);
    newfcinfo->args[3].isnull = false;
 
-   relation_statistics_update(newfcinfo, ERROR, false);
+   relation_statistics_update(newfcinfo, ERROR);
    PG_RETURN_VOID();
 }
 
@@ -261,7 +217,7 @@ pg_restore_relation_stats(PG_FUNCTION_ARGS)
                                          relarginfo, WARNING))
        result = false;
 
-   if (!relation_statistics_update(positional_fcinfo, WARNING, true))
+   if (!relation_statistics_update(positional_fcinfo, WARNING))
        result = false;
 
    PG_RETURN_BOOL(result);

diff --git a/src/test/regress/expected/stats_import.out b/src/test/regress/expected/stats_import.out
index 0e8491131e3a048c6b0746848bf5cc803f92c5dd..d6713eacc2c61587449cadfdad4315b9f88c3e19 100644 (file)
--- a/src/test/regress/expected/stats_import.out
+++ b/src/test/regress/expected/stats_import.out
@@ -143,39 +143,6 @@ WHERE oid = 'stats_import.test'::regclass;
        18 |       401 |             5
 (1 row)
 
--- test MVCC behavior: changes do not persist after abort (in contrast
--- to pg_restore_relation_stats(), which uses in-place updates).
-BEGIN;
-SELECT
-    pg_catalog.pg_set_relation_stats(
-        relation => 'stats_import.test'::regclass,
-        relpages => NULL::integer,
-        reltuples => 4000.0::real,
-        relallvisible => 4::integer);
- pg_set_relation_stats 
------------------------
- 
-(1 row)
-
-ABORT;
-SELECT relpages, reltuples, relallvisible
-FROM pg_class
-WHERE oid = 'stats_import.test'::regclass;
- relpages | reltuples | relallvisible 
-----------+-----------+---------------
-       18 |       401 |             5
-(1 row)
-
-BEGIN;
-SELECT
-    pg_catalog.pg_clear_relation_stats(
-        'stats_import.test'::regclass);
- pg_clear_relation_stats 
--------------------------
- 
-(1 row)
-
-ABORT;
 SELECT relpages, reltuples, relallvisible
 FROM pg_class
 WHERE oid = 'stats_import.test'::regclass;
@@ -836,25 +803,6 @@ WHERE oid = 'stats_import.test'::regclass;
 (1 row)
 
 -- ok: just relpages
-SELECT pg_restore_relation_stats(
-        'relation', 'stats_import.test'::regclass,
-        'version', 150000::integer,
-        'relpages', '15'::integer);
- pg_restore_relation_stats 
----------------------------
- t
-(1 row)
-
-SELECT relpages, reltuples, relallvisible
-FROM pg_class
-WHERE oid = 'stats_import.test'::regclass;
- relpages | reltuples | relallvisible 
-----------+-----------+---------------
-       15 |       400 |             4
-(1 row)
-
--- test non-MVCC behavior: new value should persist after abort
-BEGIN;
 SELECT pg_restore_relation_stats(
         'relation', 'stats_import.test'::regclass,
         'version', 150000::integer,
@@ -864,7 +812,6 @@ SELECT pg_restore_relation_stats(
  t
 (1 row)
 
-ABORT;
 SELECT relpages, reltuples, relallvisible
 FROM pg_class
 WHERE oid = 'stats_import.test'::regclass;

diff --git a/src/test/regress/sql/stats_import.sql b/src/test/regress/sql/stats_import.sql
index 5e24c779d80071c1f4efc2ae2d0b18e0f16500f5..9740ab3ff0254fc1833def732474611335c3f1ca 100644 (file)
--- a/src/test/regress/sql/stats_import.sql
+++ b/src/test/regress/sql/stats_import.sql
@@ -100,27 +100,6 @@ SELECT relpages, reltuples, relallvisible
 FROM pg_class
 WHERE oid = 'stats_import.test'::regclass;
 
--- test MVCC behavior: changes do not persist after abort (in contrast
--- to pg_restore_relation_stats(), which uses in-place updates).
-BEGIN;
-SELECT
-    pg_catalog.pg_set_relation_stats(
-        relation => 'stats_import.test'::regclass,
-        relpages => NULL::integer,
-        reltuples => 4000.0::real,
-        relallvisible => 4::integer);
-ABORT;
-
-SELECT relpages, reltuples, relallvisible
-FROM pg_class
-WHERE oid = 'stats_import.test'::regclass;
-
-BEGIN;
-SELECT
-    pg_catalog.pg_clear_relation_stats(
-        'stats_import.test'::regclass);
-ABORT;
-
 SELECT relpages, reltuples, relallvisible
 FROM pg_class
 WHERE oid = 'stats_import.test'::regclass;
@@ -649,22 +628,10 @@ FROM pg_class
 WHERE oid = 'stats_import.test'::regclass;
 
 -- ok: just relpages
-SELECT pg_restore_relation_stats(
-        'relation', 'stats_import.test'::regclass,
-        'version', 150000::integer,
-        'relpages', '15'::integer);
-
-SELECT relpages, reltuples, relallvisible
-FROM pg_class
-WHERE oid = 'stats_import.test'::regclass;
-
--- test non-MVCC behavior: new value should persist after abort
-BEGIN;
 SELECT pg_restore_relation_stats(
         'relation', 'stats_import.test'::regclass,
         'version', 150000::integer,
         'relpages', '16'::integer);
-ABORT;
 
 SELECT relpages, reltuples, relallvisible
 FROM pg_class