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Allow HOT updates for some expression indexes

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If the value of an index expression is unchanged after UPDATE,
allow HOT updates where previously we disallowed them, giving
a significant performance boost in those cases.

Particularly useful for indexes such as JSON->>field where the
JSON value changes but the indexed value does not.

Submitted as "surjective indexes" patch, now enabled by use
of new "recheck_on_update" parameter.

Author: Konstantin Knizhnik
Reviewer: Simon Riggs, with much wordsmithing and some cleanup
This commit is contained in:
Simon Riggs
2018-03-27 19:57:02 +01:00
parent 1944cdc982
commit c203d6cf81
13 changed files with 395 additions and 22 deletions
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61
src/test/regress/expected/func_index.out Normal file
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@ -0,0 +1,61 @@
create table keyvalue(id integer primary key, info jsonb);
create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=false);
insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
0
(1 row)
drop table keyvalue;
create table keyvalue(id integer primary key, info jsonb);
create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=true);
insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
1
(1 row)
update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
1
(1 row)
update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
2
(1 row)
drop table keyvalue;
create table keyvalue(id integer primary key, info jsonb);
create index nameindex on keyvalue((info->>'name'));
insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
1
(1 row)
update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
1
(1 row)
update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
pg_stat_get_xact_tuples_hot_updated
-------------------------------------
2
(1 row)
drop table keyvalue;

2
src/test/regress/parallel_schedule
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@ -84,7 +84,7 @@ test: select_into select_distinct select_distinct_on select_implicit select_havi
# ----------
# Another group of parallel tests
# ----------
test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password
test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password func_index
# ----------
# Another group of parallel tests

1
src/test/regress/serial_schedule
View File

@ -101,6 +101,7 @@ test: portals
test: arrays
test: btree_index
test: hash_index
test: func_index
test: update
test: delete
test: namespace

30
src/test/regress/sql/func_index.sql Normal file
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@ -0,0 +1,30 @@
create table keyvalue(id integer primary key, info jsonb);
create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=false);
insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
drop table keyvalue;
create table keyvalue(id integer primary key, info jsonb);
create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=true);
insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
drop table keyvalue;
create table keyvalue(id integer primary key, info jsonb);
create index nameindex on keyvalue((info->>'name'));
insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
drop table keyvalue;