Re: SELECT and RowExclusiveLock

On 04/07/2017 01:25 PM, Tim Nelson wrote:
> New to Postgres and I have never seen this condition. We are getting
> test applications hanging on SELECT statements with a RowExclusiveLock.
> How can a SELECT cause a RowExclusiveLock?
>
> relname | pid | mode | granted
> --------------------------+-------+------------------+---------
> sales_transaction_detail | 392 | RowExclusiveLock | t
> sales_transaction_detail | 19077 | RowExclusiveLock | t
> sales_transaction_header | 32661 | RowExclusiveLock | t
> sales_transaction_header | 392 | RowExclusiveLock | t
> sales_transaction_header | 19077 | RowExclusiveLock | t
>
> pid | age | usename |
> query
> -------+------------------+----------+----------------------------------------------------------------------------------
> 32661 | -07:42:39.289945 | postgres | UPDATE "sales_transaction_header"
> SET "create_datetime" = '2017-04-07T02:20:39.4
> 19077 | -07:42:15.976288 | postgres | SELECT "price_benefit"."id",
> "price_benefit"."create_datetime", "price_benefit".
> 392 | -07:01:44.121346 | postgres | SELECT "price_benefit"."id",
> "price_benefit"."create_datetime", "price_benefit".

It would help to have:

1) Schema definitions for sales_transaction_detail and
sales_transaction_header

2) The complete queries.

3) And just for grins the Postgres version.

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com