Remove redundant and ineffective test for btree insertion fast path.

indexing.sql's test for this feature was added along with the
feature in commit 2b27273.  However, shortly later that test was
rendered ineffective by commit 074251d, which limited when the
optimization would be applied, so that the test didn't test it.
Since then, commit dd299df added new tests (in btree_index.sql)
that actually do test the feature.  Code coverage comparisons
confirm that this test sequence adds no meaningful coverage, and
it's rather expensive, accounting for nearly half of the runtime
of indexing.sql according to my measurements.  So let's remove it.

Per advice from Peter Geoghegan.

Discussion: https://postgr.es/m/735.1554935715@sss.pgh.pa.us

Author: tglsfdc

src/test/regress/expected/indexing.out

@@ -1165,239 +1165,6 @@ select tableoid::regclass, * from idxpart order by a;
 (8 rows)
 
 drop table idxpart;
--- test fastpath mechanism for index insertion
-create table fastpath (a int, b text, c numeric);
-create unique index fpindex1 on fastpath(a);
-insert into fastpath values (1, 'b1', 100.00);
-insert into fastpath values (1, 'b1', 100.00); -- unique key check
-ERROR:  duplicate key value violates unique constraint "fpindex1"
-DETAIL:  Key (a)=(1) already exists.
-truncate fastpath;
-insert into fastpath select generate_series(1,10000), 'b', 100;
--- vacuum the table so as to improve chances of index-only scans. we can't
--- guarantee if index-only scans will be picked up in all cases or not, but
--- that fuzziness actually helps the test.
-vacuum fastpath;
-set enable_seqscan to false;
-set enable_bitmapscan to false;
-select sum(a) from fastpath where a = 6456;
- sum  
-------
- 6456
-(1 row)
-
-select sum(a) from fastpath where a >= 5000 and a < 5700;
-   sum   
----------
- 3744650
-(1 row)
-
--- drop the only index on the table and compute hashes for
--- a few queries which orders the results in various different ways.
-drop index fpindex1;
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 6167a852b3e0679886b84a5405b5b53d
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- dfcf2bd5e5fea8397d47b2fd14618d31
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
--- now create a multi-column index with both column asc
-create index fpindex2 on fastpath(a, b);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
--- again, vacuum here either forces index-only scans or creates fuzziness
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 6167a852b3e0679886b84a5405b5b53d
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- dfcf2bd5e5fea8397d47b2fd14618d31
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
--- same queries with a different kind of index now. the final result must not
--- change irrespective of what kind of index we have.
-drop index fpindex2;
-create index fpindex3 on fastpath(a desc, b asc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 6167a852b3e0679886b84a5405b5b53d
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- dfcf2bd5e5fea8397d47b2fd14618d31
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
--- repeat again
-drop index fpindex3;
-create index fpindex4 on fastpath(a asc, b desc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 6167a852b3e0679886b84a5405b5b53d
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- dfcf2bd5e5fea8397d47b2fd14618d31
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
--- and again, this time indexing by (b, a). Note that column "b" has non-unique
--- values.
-drop index fpindex4;
-create index fpindex5 on fastpath(b asc, a desc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 6167a852b3e0679886b84a5405b5b53d
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- dfcf2bd5e5fea8397d47b2fd14618d31
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
--- one last time
-drop index fpindex5;
-create index fpindex6 on fastpath(b desc, a desc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 6167a852b3e0679886b84a5405b5b53d
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- dfcf2bd5e5fea8397d47b2fd14618d31
-(1 row)
-
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-               md5                
-----------------------------------
- 2ca216010a558a52d7df12f76dfc77ab
-(1 row)
-
-drop table fastpath;
 -- intentionally leave some objects around
 create table idxpart (a int) partition by range (a);
 create table idxpart1 partition of idxpart for values from (0) to (100);

src/test/regress/sql/indexing.sql

@@ -620,120 +620,6 @@ insert into idxpart values (857142, 'six');
 select tableoid::regclass, * from idxpart order by a;
 drop table idxpart;
 
--- test fastpath mechanism for index insertion
-create table fastpath (a int, b text, c numeric);
-create unique index fpindex1 on fastpath(a);
-
-insert into fastpath values (1, 'b1', 100.00);
-insert into fastpath values (1, 'b1', 100.00); -- unique key check
-
-truncate fastpath;
-insert into fastpath select generate_series(1,10000), 'b', 100;
-
--- vacuum the table so as to improve chances of index-only scans. we can't
--- guarantee if index-only scans will be picked up in all cases or not, but
--- that fuzziness actually helps the test.
-vacuum fastpath;
-
-set enable_seqscan to false;
-set enable_bitmapscan to false;
-
-select sum(a) from fastpath where a = 6456;
-select sum(a) from fastpath where a >= 5000 and a < 5700;
-
--- drop the only index on the table and compute hashes for
--- a few queries which orders the results in various different ways.
-drop index fpindex1;
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-
--- now create a multi-column index with both column asc
-create index fpindex2 on fastpath(a, b);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
--- again, vacuum here either forces index-only scans or creates fuzziness
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-
--- same queries with a different kind of index now. the final result must not
--- change irrespective of what kind of index we have.
-drop index fpindex2;
-create index fpindex3 on fastpath(a desc, b asc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-
--- repeat again
-drop index fpindex3;
-create index fpindex4 on fastpath(a asc, b desc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-
--- and again, this time indexing by (b, a). Note that column "b" has non-unique
--- values.
-drop index fpindex4;
-create index fpindex5 on fastpath(b asc, a desc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-
--- one last time
-drop index fpindex5;
-create index fpindex6 on fastpath(b desc, a desc);
-truncate fastpath;
-insert into fastpath select y.x, 'b' || (y.x/10)::text, 100 from (select generate_series(1,10000) as x) y;
-vacuum fastpath;
-select md5(string_agg(a::text, b order by a, b asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by a desc, b desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a desc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-select md5(string_agg(a::text, b order by b, a asc)) from fastpath
-	where a >= 1000 and a < 2000 and b > 'b1' and b < 'b3';
-
-drop table fastpath;
-
 -- intentionally leave some objects around
 create table idxpart (a int) partition by range (a);
 create table idxpart1 partition of idxpart for values from (0) to (100);