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Fix pg_statio_all_tables view for multiple TOAST indexes.

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A TOAST table can normally have only one index, but there are corner
cases where it has more; for example, transiently during REINDEX
CONCURRENTLY.  In such a case, the pg_statio_all_tables view produced
multiple rows for the owning table, one per TOAST index.  Refactor the
view to avoid that, instead summing the stats across all the indexes,
as we do for regular table indexes.

While this has been wrong for a long time, back-patching seems unwise
due to the difficulty of putting a system view change into back
branches.

Andrei Zubkov, tweaked a bit by me

Discussion: https://postgr.es/m/acefef4189706971fc475f912c1afdab1c48d627.camel@moonset.ru
This commit is contained in:
Tom Lane
2022-03-24 16:33:13 -04:00
parent 7dac61402e
commit ce95c54376
3 changed files with 34 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
src/backend/catalog/system_views.sql
View File

@ -727,22 +727,31 @@ CREATE VIEW pg_statio_all_tables AS
pg_stat_get_blocks_fetched(C.oid) -
pg_stat_get_blocks_hit(C.oid) AS heap_blks_read,
pg_stat_get_blocks_hit(C.oid) AS heap_blks_hit,
sum(pg_stat_get_blocks_fetched(I.indexrelid) -
pg_stat_get_blocks_hit(I.indexrelid))::bigint AS idx_blks_read,
sum(pg_stat_get_blocks_hit(I.indexrelid))::bigint AS idx_blks_hit,
I.idx_blks_read AS idx_blks_read,
I.idx_blks_hit AS idx_blks_hit,
pg_stat_get_blocks_fetched(T.oid) -
pg_stat_get_blocks_hit(T.oid) AS toast_blks_read,
pg_stat_get_blocks_hit(T.oid) AS toast_blks_hit,
pg_stat_get_blocks_fetched(X.indexrelid) -
pg_stat_get_blocks_hit(X.indexrelid) AS tidx_blks_read,
pg_stat_get_blocks_hit(X.indexrelid) AS tidx_blks_hit
X.idx_blks_read AS tidx_blks_read,
X.idx_blks_hit AS tidx_blks_hit
FROM pg_class C LEFT JOIN
pg_index I ON C.oid = I.indrelid LEFT JOIN
pg_class T ON C.reltoastrelid = T.oid LEFT JOIN
pg_index X ON T.oid = X.indrelid
pg_class T ON C.reltoastrelid = T.oid
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE C.relkind IN ('r', 't', 'm')
GROUP BY C.oid, N.nspname, C.relname, T.oid, X.indexrelid;
LEFT JOIN LATERAL (
SELECT sum(pg_stat_get_blocks_fetched(indexrelid) -
pg_stat_get_blocks_hit(indexrelid))::bigint
AS idx_blks_read,
sum(pg_stat_get_blocks_hit(indexrelid))::bigint
AS idx_blks_hit
FROM pg_index WHERE indrelid = C.oid ) I ON true
LEFT JOIN LATERAL (
SELECT sum(pg_stat_get_blocks_fetched(indexrelid) -
pg_stat_get_blocks_hit(indexrelid))::bigint
AS idx_blks_read,
sum(pg_stat_get_blocks_hit(indexrelid))::bigint
AS idx_blks_hit
FROM pg_index WHERE indrelid = T.oid ) X ON true
WHERE C.relkind IN ('r', 't', 'm');
CREATE VIEW pg_statio_sys_tables AS
SELECT * FROM pg_statio_all_tables

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 202203221
#define CATALOG_VERSION_NO 202203241
#endif

21
src/test/regress/expected/rules.out
View File

@ -2269,19 +2269,24 @@ pg_statio_all_tables| SELECT c.oid AS relid,
c.relname,
(pg_stat_get_blocks_fetched(c.oid) - pg_stat_get_blocks_hit(c.oid)) AS heap_blks_read,
pg_stat_get_blocks_hit(c.oid) AS heap_blks_hit,
(sum((pg_stat_get_blocks_fetched(i.indexrelid) - pg_stat_get_blocks_hit(i.indexrelid))))::bigint AS idx_blks_read,
(sum(pg_stat_get_blocks_hit(i.indexrelid)))::bigint AS idx_blks_hit,
i.idx_blks_read,
i.idx_blks_hit,
(pg_stat_get_blocks_fetched(t.oid) - pg_stat_get_blocks_hit(t.oid)) AS toast_blks_read,
pg_stat_get_blocks_hit(t.oid) AS toast_blks_hit,
(pg_stat_get_blocks_fetched(x.indexrelid) - pg_stat_get_blocks_hit(x.indexrelid)) AS tidx_blks_read,
pg_stat_get_blocks_hit(x.indexrelid) AS tidx_blks_hit
x.idx_blks_read AS tidx_blks_read,
x.idx_blks_hit AS tidx_blks_hit
FROM ((((pg_class c
LEFT JOIN pg_index i ON ((c.oid = i.indrelid)))
LEFT JOIN pg_class t ON ((c.reltoastrelid = t.oid)))
LEFT JOIN pg_index x ON ((t.oid = x.indrelid)))
LEFT JOIN pg_namespace n ON ((n.oid = c.relnamespace)))
WHERE (c.relkind = ANY (ARRAY['r'::"char", 't'::"char", 'm'::"char"]))
GROUP BY c.oid, n.nspname, c.relname, t.oid, x.indexrelid;
LEFT JOIN LATERAL ( SELECT (sum((pg_stat_get_blocks_fetched(pg_index.indexrelid) - pg_stat_get_blocks_hit(pg_index.indexrelid))))::bigint AS idx_blks_read,
(sum(pg_stat_get_blocks_hit(pg_index.indexrelid)))::bigint AS idx_blks_hit
FROM pg_index
WHERE (pg_index.indrelid = c.oid)) i ON (true))
LEFT JOIN LATERAL ( SELECT (sum((pg_stat_get_blocks_fetched(pg_index.indexrelid) - pg_stat_get_blocks_hit(pg_index.indexrelid))))::bigint AS idx_blks_read,
(sum(pg_stat_get_blocks_hit(pg_index.indexrelid)))::bigint AS idx_blks_hit
FROM pg_index
WHERE (pg_index.indrelid = t.oid)) x ON (true))
WHERE (c.relkind = ANY (ARRAY['r'::"char", 't'::"char", 'm'::"char"]));
pg_statio_sys_indexes| SELECT pg_statio_all_indexes.relid,
pg_statio_all_indexes.indexrelid,
pg_statio_all_indexes.schemaname,