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Re: What could cause CREATE TEMP... "could not read block" error? - Mailing list pgsql-general

From Chris Richards
Subject Re: What could cause CREATE TEMP... "could not read block" error?
Date
Msg-id CAOan6Tn1A5siL4E=Aboh3UShYsNO_tNTvX1_kgoRH=8hDptZLw@mail.gmail.com
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In response to What could cause CREATE TEMP... "could not read block" error?  (Chris Richards <chris@infiniteio.com>)
Responses Re: What could cause CREATE TEMP... "could not read block" error?
Re: What could cause CREATE TEMP... "could not read block" error?
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Adrian is correct. This worked by itself whereas using it in the creation of the temporary table failed.

mdb-> SELECT pq.* FROM policyqueue AS pq
mdb-> JOIN seed_progress AS sp ON pq.id=sp.polidx;

I checked the query Albe suggested; there were two `relfilenode`s (11936 and 11937) that exhibited the error. Respectively, they were pg_depend_depender_index and pg_depend_reference_index.

Unfortunately, I didn't disable the nightly processes and something must  have(?) fixed the glitch; at midnight GMT the query ran successfully. Ugh.

If it crops up again, I have some tools to try and capture data immediately, and the suggested REINDEX since both appear to be indices.

Thanks for the help. It's appreciated.

Chris

On Fri, Nov 20, 2015 at 8:28 AM, Adrian Klaver <adrian.klaver@aklaver.com> wrote:
On 11/20/2015 06:18 AM, Albe Laurenz wrote:
Chris Richards wrote:
Howdy. I have two tables that I'm joining together and using the result to create a temporary table.
Performing the join operation works fine; it produces 0 rows (as expected). If I prepend "CREATE TEMP
tmp_policyqueue AS" to the SELECT then it generates this error:

ERROR:  could not read block 39 in file "base/16391/11937": read only 0 of 8192 bytes


$ psql
psql (9.3.9)

mdb=> CREATE TEMP TABLE tmp_policyqueue AS

mdb-> SELECT pq.* FROM policyqueue AS pq
mdb-> JOIN seed_progress AS sp ON pq.id=sp.polidx;
ERROR:  could not read block 40 in file "base/16391/11937": read only 0 of 8192 bytes

You'll also observe that the block number is changing each time I execute the command. I know very
little about postgres internal structure so it may be irrelevant. I've left my database in this state
should extra information be needed.

It would be interesting to know what object is affected:

SELECT s.nspname AS schemaname, t.relname AS objectname, t.relkind
FROM pg_class t JOIN
      pg_namespace s ON t.relnamespace = s.oid
WHERE t.relfilenode = 11937;

If it is an index, REINDEX should help.

What is the statement that performs the join operation and works just fine?

 If I am following correctly it is:

mdb-> SELECT pq.* FROM policyqueue AS pq
mdb-> JOIN seed_progress AS sp ON pq.id=sp.polidx;


Yours,
Laurenz Albe



--
Adrian Klaver
adrian.klaver@aklaver.com

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