Create real array comparison functions (that use the element datatype's

comparison functions), replacing the highly bogus bitwise array_eq.  Create
a btree index opclass for ANYARRAY --- it is now possible to create indexes
on array columns.
Arrange to cache the results of catalog lookups across multiple array
operations, instead of repeating the lookups on every call.
Add string_to_array and array_to_string functions.
Remove singleton_array, array_accum, array_assign, and array_subscript
functions, since these were for proof-of-concept and not intended to become
supported functions.
Minor adjustments to behavior in some corner cases with empty or
zero-dimensional arrays.

Joe Conway (with some editorializing by Tom Lane).

src/test/regress/expected/arrays.out

@@ -178,19 +178,13 @@ SELECT ARRAY(select f2 from arrtest_f order by f2) AS "ARRAY";
 (1 row)
 
 -- functions
-SELECT singleton_array(42) AS "{42}";
- {42} 
-------
- {42}
-(1 row)
-
-SELECT array_append(singleton_array(42), 6) AS "{42,6}";
+SELECT array_append(array[42], 6) AS "{42,6}";
  {42,6} 
 --------
  {42,6}
 (1 row)
 
-SELECT array_prepend(6, singleton_array(42)) AS "{6,42}";
+SELECT array_prepend(6, array[42]) AS "{6,42}";
  {6,42} 
 --------
  {6,42}
@@ -214,24 +208,6 @@ SELECT array_cat(ARRAY[[3,4],[5,6]], ARRAY[1,2]) AS "{{3,4},{5,6},{1,2}}";
  {{3,4},{5,6},{1,2}}
 (1 row)
 
-SELECT array_subscript(n, 2) AS "1.2" FROM arrtest2;
- 1.2 
------
- 1.2
-(1 row)
-
-SELECT array_assign(n, 2, 9.99) AS "{1.1,9.99,1.3}" FROM arrtest2;
- {1.1,9.99,1.3} 
-----------------
- {1.1,9.99,1.3}
-(1 row)
-
-SELECT array_subscript(array_assign(n, 2, 9.99), 2) AS "9.99" FROM arrtest2;
- 9.99 
-------
- 9.99
-(1 row)
-
 -- operators
 SELECT a FROM arrtest WHERE b = ARRAY[[[113,142],[1,147]]];
        a       
@@ -318,3 +294,24 @@ SELECT CAST(ARRAY[[[[[['a','bb','ccc']]]]]] as text[]) as "{{{{{{a,bb,ccc}}}}}}"
  {{{{{{a,bb,ccc}}}}}}
 (1 row)
 
+-- test indexes on arrays
+create temp table arr_tbl (f1 int[] unique);
+NOTICE:  CREATE TABLE / UNIQUE will create implicit index 'arr_tbl_f1_key' for table 'arr_tbl'
+insert into arr_tbl values ('{1,2,3}');
+insert into arr_tbl values ('{1,2}');
+-- failure expected:
+insert into arr_tbl values ('{1,2,3}');
+ERROR:  Cannot insert a duplicate key into unique index arr_tbl_f1_key
+insert into arr_tbl values ('{2,3,4}');
+insert into arr_tbl values ('{1,5,3}');
+insert into arr_tbl values ('{1,2,10}');
+set enable_seqscan to off;
+select * from arr_tbl where f1 > '{1,2,3}' and f1 <= '{1,5,3}';
+    f1    
+----------
+ {1,2,10}
+ {1,5,3}
+(2 rows)
+
+-- note: if above select doesn't produce the expected tuple order,
+-- then you didn't get an indexscan plan, and something is busted.

src/test/regress/sql/arrays.sql

@@ -130,15 +130,11 @@ SELECT ARRAY[ARRAY['hello'],ARRAY['world']];
 SELECT ARRAY(select f2 from arrtest_f order by f2) AS "ARRAY";
 
 -- functions
-SELECT singleton_array(42) AS "{42}";
-SELECT array_append(singleton_array(42), 6) AS "{42,6}";
-SELECT array_prepend(6, singleton_array(42)) AS "{6,42}";
+SELECT array_append(array[42], 6) AS "{42,6}";
+SELECT array_prepend(6, array[42]) AS "{6,42}";
 SELECT array_cat(ARRAY[1,2], ARRAY[3,4]) AS "{{1,2},{3,4}}";
 SELECT array_cat(ARRAY[1,2], ARRAY[[3,4],[5,6]]) AS "{{1,2},{3,4},{5,6}}";
 SELECT array_cat(ARRAY[[3,4],[5,6]], ARRAY[1,2]) AS "{{3,4},{5,6},{1,2}}";
-SELECT array_subscript(n, 2) AS "1.2" FROM arrtest2;
-SELECT array_assign(n, 2, 9.99) AS "{1.1,9.99,1.3}" FROM arrtest2;
-SELECT array_subscript(array_assign(n, 2, 9.99), 2) AS "9.99" FROM arrtest2;
 
 -- operators
 SELECT a FROM arrtest WHERE b = ARRAY[[[113,142],[1,147]]];
@@ -157,3 +153,17 @@ SELECT ARRAY[1,2,3]::text[]::int[]::float8[] is of (float8[]) as "TRUE";
 SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] AS "{{a,bc},{def,hijk}}";
 SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] is of (varchar[]) as "TRUE";
 SELECT CAST(ARRAY[[[[[['a','bb','ccc']]]]]] as text[]) as "{{{{{{a,bb,ccc}}}}}}";
+
+-- test indexes on arrays
+create temp table arr_tbl (f1 int[] unique);
+insert into arr_tbl values ('{1,2,3}');
+insert into arr_tbl values ('{1,2}');
+-- failure expected:
+insert into arr_tbl values ('{1,2,3}');
+insert into arr_tbl values ('{2,3,4}');
+insert into arr_tbl values ('{1,5,3}');
+insert into arr_tbl values ('{1,2,10}');
+set enable_seqscan to off;
+select * from arr_tbl where f1 > '{1,2,3}' and f1 <= '{1,5,3}';
+-- note: if above select doesn't produce the expected tuple order,
+-- then you didn't get an indexscan plan, and something is busted.