Fix handling of expressions and predicates in REINDEX CONCURRENTLY

When copying the definition of an index rebuilt concurrently for the new
entry, the index information was taken directly from the old index using
the relation cache.  In this case, predicates and expressions have
some post-processing to prepare things for the planner, which loses some
information including the collations added in any of them.

This inconsistency can cause issues when attempting for example a table
rewrite, and makes the new indexes rebuilt concurrently inconsistent
with the old entries.

In order to fix the problem, fetch expressions and predicates directly
from the catalog of the old entry, and fill in IndexInfo for the new
index with that.  This makes the process more consistent with
DefineIndex(), and the code is refactored with the addition of a routine
to create an IndexInfo node.

Reported-by: Manuel Rigger
Author: Michael Paquier
Discussion: https://postgr.es/m/CA+u7OA5Hp0ra235F3czPom_FyAd-3+XwSJmX95r1+sRPOJc9VQ@mail.gmail.com
Backpatch-through: 12

2 files changed, 100 insertions, 0 deletions

diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 9305649c113..c6d575a2f99 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2170,6 +2170,78 @@ Indexes:
     "concur_reindex_ind5" UNIQUE, btree (c1)
 
 DROP TABLE concur_reindex_tab4;
+-- Check handling of indexes with expressions and predicates.  The
+-- definitions of the rebuilt indexes should match the original
+-- definitions.
+CREATE TABLE concur_exprs_tab (c1 int , c2 boolean);
+INSERT INTO concur_exprs_tab (c1, c2) VALUES (1369652450, FALSE),
+  (414515746, TRUE),
+  (897778963, FALSE);
+CREATE UNIQUE INDEX concur_exprs_index_expr
+  ON concur_exprs_tab ((c1::text COLLATE "C"));
+CREATE UNIQUE INDEX concur_exprs_index_pred ON concur_exprs_tab (c1)
+  WHERE (c1::text > 500000000::text COLLATE "C");
+CREATE UNIQUE INDEX concur_exprs_index_pred_2
+  ON concur_exprs_tab ((1 / c1))
+  WHERE ('-H') >= (c2::TEXT) COLLATE "C";
+SELECT pg_get_indexdef('concur_exprs_index_expr'::regclass);
+                                                pg_get_indexdef                                                
+---------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_expr ON public.concur_exprs_tab USING btree (((c1)::text) COLLATE "C")
+(1 row)
+
+SELECT pg_get_indexdef('concur_exprs_index_pred'::regclass);
+                                                               pg_get_indexdef                                                                
+----------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_pred ON public.concur_exprs_tab USING btree (c1) WHERE ((c1)::text > ((500000000)::text COLLATE "C"))
+(1 row)
+
+SELECT pg_get_indexdef('concur_exprs_index_pred_2'::regclass);
+                                                                 pg_get_indexdef                                                                  
+--------------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_pred_2 ON public.concur_exprs_tab USING btree (((1 / c1))) WHERE ('-H'::text >= ((c2)::text COLLATE "C"))
+(1 row)
+
+REINDEX TABLE CONCURRENTLY concur_exprs_tab;
+SELECT pg_get_indexdef('concur_exprs_index_expr'::regclass);
+                                                pg_get_indexdef                                                
+---------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_expr ON public.concur_exprs_tab USING btree (((c1)::text) COLLATE "C")
+(1 row)
+
+SELECT pg_get_indexdef('concur_exprs_index_pred'::regclass);
+                                                               pg_get_indexdef                                                                
+----------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_pred ON public.concur_exprs_tab USING btree (c1) WHERE ((c1)::text > ((500000000)::text COLLATE "C"))
+(1 row)
+
+SELECT pg_get_indexdef('concur_exprs_index_pred_2'::regclass);
+                                                                 pg_get_indexdef                                                                  
+--------------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_pred_2 ON public.concur_exprs_tab USING btree (((1 / c1))) WHERE ('-H'::text >= ((c2)::text COLLATE "C"))
+(1 row)
+
+-- ALTER TABLE recreates the indexes, which should keep their collations.
+ALTER TABLE concur_exprs_tab ALTER c2 TYPE TEXT;
+SELECT pg_get_indexdef('concur_exprs_index_expr'::regclass);
+                                                pg_get_indexdef                                                
+---------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_expr ON public.concur_exprs_tab USING btree (((c1)::text) COLLATE "C")
+(1 row)
+
+SELECT pg_get_indexdef('concur_exprs_index_pred'::regclass);
+                                                               pg_get_indexdef                                                                
+----------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_pred ON public.concur_exprs_tab USING btree (c1) WHERE ((c1)::text > ((500000000)::text COLLATE "C"))
+(1 row)
+
+SELECT pg_get_indexdef('concur_exprs_index_pred_2'::regclass);
+                                                             pg_get_indexdef                                                              
+------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX concur_exprs_index_pred_2 ON public.concur_exprs_tab USING btree (((1 / c1))) WHERE ('-H'::text >= (c2 COLLATE "C"))
+(1 row)
+
+DROP TABLE concur_exprs_tab;
 --
 -- REINDEX SCHEMA
 --
diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index cd46f071bdc..f96bebf410d 100644
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -872,6 +872,34 @@ REINDEX INDEX CONCURRENTLY concur_reindex_ind5;
 \d concur_reindex_tab4
 DROP TABLE concur_reindex_tab4;
 
+-- Check handling of indexes with expressions and predicates.  The
+-- definitions of the rebuilt indexes should match the original
+-- definitions.
+CREATE TABLE concur_exprs_tab (c1 int , c2 boolean);
+INSERT INTO concur_exprs_tab (c1, c2) VALUES (1369652450, FALSE),
+  (414515746, TRUE),
+  (897778963, FALSE);
+CREATE UNIQUE INDEX concur_exprs_index_expr
+  ON concur_exprs_tab ((c1::text COLLATE "C"));
+CREATE UNIQUE INDEX concur_exprs_index_pred ON concur_exprs_tab (c1)
+  WHERE (c1::text > 500000000::text COLLATE "C");
+CREATE UNIQUE INDEX concur_exprs_index_pred_2
+  ON concur_exprs_tab ((1 / c1))
+  WHERE ('-H') >= (c2::TEXT) COLLATE "C";
+SELECT pg_get_indexdef('concur_exprs_index_expr'::regclass);
+SELECT pg_get_indexdef('concur_exprs_index_pred'::regclass);
+SELECT pg_get_indexdef('concur_exprs_index_pred_2'::regclass);
+REINDEX TABLE CONCURRENTLY concur_exprs_tab;
+SELECT pg_get_indexdef('concur_exprs_index_expr'::regclass);
+SELECT pg_get_indexdef('concur_exprs_index_pred'::regclass);
+SELECT pg_get_indexdef('concur_exprs_index_pred_2'::regclass);
+-- ALTER TABLE recreates the indexes, which should keep their collations.
+ALTER TABLE concur_exprs_tab ALTER c2 TYPE TEXT;
+SELECT pg_get_indexdef('concur_exprs_index_expr'::regclass);
+SELECT pg_get_indexdef('concur_exprs_index_pred'::regclass);
+SELECT pg_get_indexdef('concur_exprs_index_pred_2'::regclass);
+DROP TABLE concur_exprs_tab;
+
 --
 -- REINDEX SCHEMA
 --