Re: Feature: temporary materialized views

[Michael Paquier]

On Tue, Feb 05, 2019 at 06:56:00PM +0100, Andreas Karlsson wrote:
> I guess that I could fix that for the second case as soon as I understand
> how much of the portal stuff can be skipped in ExecuteQuery(). But I am not
> sure what we should do with EXPLAIN ANALYZE ... NO DATA. It feels like a
> contraction to me. Should we just raise an error? Or should we try to
> preserve the current behavior where you see something like the
> below?

This grammar is documented, so it seems to me that it would be just
annoying for users relying on it to throw an error for a pattern that
simply worked, particularly if a driver layer is using it.

The issue this outlines is that we have a gap in the tests for a
subset of the grammar, which is not a good thing.

If I put Assert(!into->skipData) at the beginning of intorel_startup()
then the main regression test suite is able to pass, both on HEAD and
with your patch.  There is one test for CTAS EXECUTE in prepare.sql,
so let's add a pattern with WITH NO DATA there for the first pattern.
Adding a second test with EXPLAIN SELECT INTO into select_into.sql
also looks like a good thing.

Attached is a patch to do that and close the gap.  With that, we will
be able to check for inconsistencies better when working on the
follow-up patches.  What do you think?
--
Michael

diff --git a/src/test/regress/expected/prepare.out b/src/test/regress/expected/prepare.out
index d07c0cc9c9..717732300d 100644
--- a/src/test/regress/expected/prepare.out
+++ b/src/test/regress/expected/prepare.out
@@ -145,6 +145,13 @@ SELECT * FROM q5_prep_results;
     9961 |    2058 |   1 |    1 |   1 |      1 |      61 |      961 |        1961 |      4961 |     9961 | 122 |  123 | DTAAAA   | EBDAAA   | OOOOxx
 (16 rows)
 
+CREATE TEMPORARY TABLE q5_prep_nodata AS EXECUTE q5(200, 'DTAAAA')
+    WITH NO DATA;
+SELECT * FROM q5_prep_nodata;
+ unique1 | unique2 | two | four | ten | twenty | hundred | thousand | twothousand | fivethous | tenthous | odd | even | stringu1 | stringu2 | string4 
+---------+---------+-----+------+-----+--------+---------+----------+-------------+-----------+----------+-----+------+----------+----------+---------
+(0 rows)
+
 -- unknown or unspecified parameter types: should succeed
 PREPARE q6 AS
     SELECT * FROM tenk1 WHERE unique1 = $1 AND stringu1 = $2;
diff --git a/src/test/regress/expected/select_into.out b/src/test/regress/expected/select_into.out
index 942f975e95..f373fae679 100644
--- a/src/test/regress/expected/select_into.out
+++ b/src/test/regress/expected/select_into.out
@@ -112,14 +112,15 @@ SELECT * FROM created_table;
  4567890123456789 | -4567890123456789
 (5 rows)
 
--- Try EXPLAIN ANALYZE SELECT INTO, but hide the output since it won't
--- be stable.
+-- Try EXPLAIN ANALYZE SELECT INTO and EXPLAIN ANALYZE CREATE TABLE AS
+-- WITH NO DATA, but hide the outputs since they won't be stable.
 DO $$
 BEGIN
 	EXECUTE 'EXPLAIN ANALYZE SELECT * INTO TABLE easi FROM int8_tbl';
+	EXECUTE 'EXPLAIN ANALYZE CREATE TABLE easi2 AS SELECT * FROM int8_tbl WITH NO DATA';
 END$$;
 DROP TABLE created_table;
-DROP TABLE easi;
+DROP TABLE easi, easi2;
 --
 -- Disallowed uses of SELECT ... INTO.  All should fail
 --
diff --git a/src/test/regress/sql/prepare.sql b/src/test/regress/sql/prepare.sql
index 7fe8c8d7f5..985d0f05c9 100644
--- a/src/test/regress/sql/prepare.sql
+++ b/src/test/regress/sql/prepare.sql
@@ -61,6 +61,9 @@ PREPARE q5(int, text) AS
 	ORDER BY unique1;
 CREATE TEMPORARY TABLE q5_prep_results AS EXECUTE q5(200, 'DTAAAA');
 SELECT * FROM q5_prep_results;
+CREATE TEMPORARY TABLE q5_prep_nodata AS EXECUTE q5(200, 'DTAAAA')
+    WITH NO DATA;
+SELECT * FROM q5_prep_nodata;
 
 -- unknown or unspecified parameter types: should succeed
 PREPARE q6 AS
diff --git a/src/test/regress/sql/select_into.sql b/src/test/regress/sql/select_into.sql
index 62eddeed9d..a708fef0ea 100644
--- a/src/test/regress/sql/select_into.sql
+++ b/src/test/regress/sql/select_into.sql
@@ -85,15 +85,16 @@ SELECT make_table();
 
 SELECT * FROM created_table;
 
--- Try EXPLAIN ANALYZE SELECT INTO, but hide the output since it won't
--- be stable.
+-- Try EXPLAIN ANALYZE SELECT INTO and EXPLAIN ANALYZE CREATE TABLE AS
+-- WITH NO DATA, but hide the outputs since they won't be stable.
 DO $$
 BEGIN
 	EXECUTE 'EXPLAIN ANALYZE SELECT * INTO TABLE easi FROM int8_tbl';
+	EXECUTE 'EXPLAIN ANALYZE CREATE TABLE easi2 AS SELECT * FROM int8_tbl WITH NO DATA';
 END$$;
 
 DROP TABLE created_table;
-DROP TABLE easi;
+DROP TABLE easi, easi2;
 
 --
 -- Disallowed uses of SELECT ... INTO.  All should fail

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