Relation cache invalidation on replica

Session opened on replica doesn't see concurrently created indexes at this
time on master.

We have master and replica:

1. master: pgbench -i -s 10

2. replica:
explain (analyze,verbose) select * from pgbench_accounts where abalance = 1;

3. master:
ALTER INDEX pgbench_accounts_abalance_idx RENAME TO
pgbench_accounts_abalance_idx_delme;
CREATE INDEX CONCURRENTLY pgbench_accounts_abalance_idx ON pgbench_accounts
USING btree (abalance);
DROP INDEX pgbench_accounts_abalance_idx_delme;

4. at this time on replica:

explain (analyze,verbose) select * from pgbench_accounts where abalance = 1;
pgbench=# explain (analyze,verbose) select * from pgbench_accounts where
abalance = 1;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------
Index Scan using pgbench_accounts_abalance_idx on public.pgbench_accounts
(cost=0.42..4.44 rows=1 width=97) (actual time=655.781..655.781 rows=0
loops=1)
Output: aid, bid, abalance, filler
Index Cond: (pgbench_accounts.abalance = 1)
Planning time: 9388.259 ms
Execution time: 655.900 ms
(5 rows)

pgbench=# explain (analyze,verbose) select * from pgbench_accounts where
abalance = 1;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------
Index Scan using pgbench_accounts_abalance_idx_delme on
public.pgbench_accounts (cost=0.42..4.44 rows=1 width=97) (actual
time=0.014..0.014 rows=0 loops=1)
Output: aid, bid, abalance, filler
Index Cond: (pgbench_accounts.abalance = 1)
Planning time: 0.321 ms
Execution time: 0.049 ms
(5 rows)

pgbench=# explain (analyze,verbose) select * from pgbench_accounts where
abalance = 1;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------
Seq Scan on public.pgbench_accounts (cost=0.00..28894.00 rows=1 width=97)
(actual time=3060.451..3060.451 rows=0 loops=1)
Output: aid, bid, abalance, filler
Filter: (pgbench_accounts.abalance = 1)
Rows Removed by Filter: 1000000
Planning time: 0.087 ms
Execution time: 3060.484 ms
(6 rows)

pgbench=# \d+ pgbench_accounts
Table "public.pgbench_accounts"
Column | Type | Modifiers | Storage | Stats target | Description
--------------------------------------------------+-----------
aid | integer | not null | plain | |
bid | integer | | plain | |
abalance | integer | | plain | |
filler | character(84) | | extended | |
Indexes:
"pgbench_accounts_pkey" PRIMARY KEY, btree (aid)
"pgbench_accounts_abalance_idx" btree (abalance)
Options: fillfactor=100

​New opened session successfully uses this index.
Tested with PostgreSQL 9.5.1.

---
Dmitry Vasilyev
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company