Re: Duplicate Index Creation

Results of \d (without all the column defs):

Indexes:
"input_transaction_snbs_prod_pkey" PRIMARY KEY, btree (id)
"i1" btree (trans_client)
Check constraints:
"chk_charge" CHECK (charge_type IS NULL OR charge_type = 'Recurring'::text OR charge_type = 'Usage'::text OR charge_type = 'Fee'::text OR charge_type = 'Equipment'::text OR charge_type = 'One-t
ime'::text OR charge_type = 'Reversal'::text OR charge_type = 'Adjustment'::text)

------------------------------------------------------------------------------------------

Results of changing the query to add schemaname and join on relid:

schema_name | table_name | index_name | times_used | table_size | index_size | num_writes
-------------+------------------------+------------+------------+------------+------------+------------
snbs | input_transaction_snbs | i1 | 0 | 2932 MB | 304242688 | 10350357
snbs | input_transaction_snbs | i1 | 0 | 2932 MB | 304242688 | 10350357
(2 rows)

----------------------------------------------------------------------------------------------

Results of removing pg_indexes from query and adding pg_get_indexdef:

table_name | index_name | times_used | index_def | table_size | index_size |
num_writes
------------------------+----------------------------------+------------+-------------------------------------------------------------------------------------------------+------------+------------+
------------
input_transaction_snbs | i1 | 0 | CREATE INDEX i1 ON input_transaction_snbs USING btree (trans_client) | 2932 MB | 304242688 |
10350357
input_transaction_snbs | input_transaction_snbs_prod_pkey | 0 | CREATE UNIQUE INDEX input_transaction_snbs_prod_pkey ON input_transaction_snbs USING btree (id) | 2932 MB | 232505344 |
10350357
(2 rows)

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The thing is, if I drop that index and run that originally posted query I get no results. When I create the index and run the query I get the duplicate entries. Also, if I do not limit that query to input_transaction_snbs and run it against everything, input_transaction_snbs is the only table that shows up with duplicate entries.

Sam

-----Original Message-----
From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
Sent: Tuesday, 3 July 2012 11:58 AM
To: Samuel Stearns
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: [ADMIN] Duplicate Index Creation

Samuel Stearns <SStearns(at)internode(dot)com(dot)au> writes:
> I create an index as: ...
> which is creating a 2nd duplicate index in error as this query shows:

> SELECT idstat.relname AS table_name,
> idstat.indexrelname AS index_name,
> idstat.idx_scan AS times_used,
> pg_size_pretty(pg_relation_size(idstat.relid)) AS table_size,
> pg_relation_size(indexrelid) AS index_size,
> n_tup_upd + n_tup_ins + n_tup_del as num_writes FROM
> pg_stat_user_indexes AS idstat JOIN pg_indexes ON indexrelname =
> indexname JOIN pg_stat_user_tables AS tabstat ON idstat.relname =
> tabstat.relname WHERE indexdef !~* 'unique'
> AND idstat.relname = 'input_transaction_snbs'
> ORDER BY index_size desc;

I don't think that query proves much at all: indexname is not a unique key for pg_indexes, nor is relname a unique key for pg_stat_user_tables, so most likely you're getting an unrelated hit in one or the other of those views.

Personally I'd rely on the table OID columns (relid) to join the two pg_stat views. If you want to join to pg_indexes it looks like you need to compare all of schemaname, tablename, indexname to be safe.
But really you could skip that join and just use pg_get_indexdef(indexrelid).

regards, tom lane