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Allow CHECK constraints to be placed on foreign tables.

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As with NOT NULL constraints, we consider that such constraints are merely
reports of constraints that are being enforced by the remote server (or
other underlying storage mechanism).  Their only real use is to allow
planner optimizations, for example in constraint-exclusion checks.  Thus,
the code changes here amount to little more than removal of the error that
was formerly thrown for applying CHECK to a foreign table.

(In passing, do a bit of cleanup of the ALTER FOREIGN TABLE reference page,
which had accumulated some weird decisions about ordering etc.)

Shigeru Hanada and Etsuro Fujita, reviewed by Kyotaro Horiguchi and
Ashutosh Bapat.
This commit is contained in:
Tom Lane
2014-12-17 17:00:53 -05:00
parent ce01548d4f
commit fc2ac1fb41
11 changed files with 437 additions and 67 deletions
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32
contrib/file_fdw/output/file_fdw.source
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@ -78,7 +78,7 @@ ERROR: COPY null representation cannot use newline or carriage return
CREATE FOREIGN TABLE tbl () SERVER file_server; -- ERROR
ERROR: filename is required for file_fdw foreign tables
CREATE FOREIGN TABLE agg_text (
a int2,
a int2 CHECK (a >= 0),
b float4
) SERVER file_server
OPTIONS (format 'text', filename '@abs_srcdir@/data/agg.data', delimiter ' ', null '\N');
@ -88,11 +88,13 @@ CREATE FOREIGN TABLE agg_csv (
b float4
) SERVER file_server
OPTIONS (format 'csv', filename '@abs_srcdir@/data/agg.csv', header 'true', delimiter ';', quote '@', escape '"', null '');
ALTER FOREIGN TABLE agg_csv ADD CHECK (a >= 0);
CREATE FOREIGN TABLE agg_bad (
a int2,
b float4
) SERVER file_server
OPTIONS (format 'csv', filename '@abs_srcdir@/data/agg.bad', header 'true', delimiter ';', quote '@', escape '"', null '');
ALTER FOREIGN TABLE agg_bad ADD CHECK (a >= 0);
-- per-column options tests
CREATE FOREIGN TABLE text_csv (
word1 text OPTIONS (force_not_null 'true'),
@ -219,6 +221,34 @@ SELECT * FROM agg_csv FOR UPDATE;
42 | 324.78
(3 rows)
-- constraint exclusion tests
\t on
EXPLAIN (VERBOSE, COSTS FALSE) SELECT * FROM agg_csv WHERE a < 0;
Foreign Scan on public.agg_csv
Output: a, b
Filter: (agg_csv.a < 0)
Foreign File: @abs_srcdir@/data/agg.csv
\t off
SELECT * FROM agg_csv WHERE a < 0;
a | b
---+---
(0 rows)
SET constraint_exclusion = 'on';
\t on
EXPLAIN (VERBOSE, COSTS FALSE) SELECT * FROM agg_csv WHERE a < 0;
Result
Output: a, b
One-Time Filter: false
\t off
SELECT * FROM agg_csv WHERE a < 0;
a | b
---+---
(0 rows)
RESET constraint_exclusion;
-- privilege tests
SET ROLE file_fdw_superuser;
SELECT * FROM agg_text ORDER BY a;