Replica string comparsion issue

[Andrey Lizenko]

Hello,
I'm observing strange behaviour on comparing ::text field with string while
quering replica.

Here is the table structure:

=# \dS+ raw.symbols_aggregates
> Table
> "raw.symbols_aggregates"
>Column   |  Type   | Collation | Nullable |
> Default | Storage  | Stats target | Description
>
> +-+---+--++--+--+-
>  id | bigint  |   | not null |
> nextval('symbols_aggregates_id_seq'::regclass) | plain|  |
>  symbol | text|   | not null |
> | extended |  |
>  id_type| bigint  |   | not null |
> | plain|  |
>  id_aggregates_list | integer |   | not null |
> | plain|  |
>  id_regionals_list  | integer |   | not null |
> | plain|  |
>  date_started   | date|   | not null |
> | plain|  |
> Indexes:
> "symbols_aggregates_pkey" PRIMARY KEY, btree (id)
> "symbols_aggregates_uniq" UNIQUE CONSTRAINT, btree (symbol, id_type,
> id_aggregates_list, id_regionals_list)
> Foreign-key constraints:
> "symbols_aggregates_id_aggregates_list_fkey" FOREIGN KEY
> (id_aggregates_list) REFERENCES aggregates_list(id)
> "symbols_aggregates_id_regionals_list_fkey" FOREIGN KEY
> (id_regionals_list) REFERENCES regionals_list(id)
> "symbols_aggregates_id_type_fkey" FOREIGN KEY (id_type) REFERENCES
> types_list(id)



Simple query on master works as expected:

> =# select symbol  from raw.symbols_aggregates where symbol='RUT';
>  symbol
> 
>  RUT
>  RUT
>  RUT
> (3 rows)


The same query on replica works only after casting to varchar, using
trim(), or something else:
(3 rows expected here)

> =# select symbol from raw.symbols_aggregates where symbol='RUT';
>  symbol
> 
> (0 rows)


with ::varchar(50) result looks correct:

=# select symbol from raw.symbols_aggregates where
> symbol::varchar(50)='RUT';
>  symbol
> 
>  RUT
>  RUT
>  RUT



There is no hidden characters, it looks identical with ::bytea

=# select symbol::bytea, 'RUT'::bytea, (symbol::varchar(50))::bytea from
> raw.symbols_aggregates where symbol::varchar(50)='RUT';
>   symbol  |  bytea   |  symbol
> --+--+--
>  \x525554 | \x525554 | \x525554
>  \x525554 | \x525554 | \x525554
>  \x525554 | \x525554 | \x525554



PostgreSQL server version is 10.3. It might be important, that master is
running on Ubuntu 16.04.4 LTS and replica on Solaris 11.3.
PostgreSQL installed from binaries, not from sources. All locales
are en_US.UTF-8

My suggestion it is a kind of collation issue, but I've no idea why :text
is not working in this case.


-- 
Regards, Andrei Lizenko

Re: Replica string comparsion issue

[Andrey Lizenko]

Re-indexing didn't help. Will check via amcheck.

Another point regarding collations: query with ORDER BY returns different
record set on master and on replica if more than one column used:

Master:

> =# select date_started, symbol from raw.symbols_aggregates order by 1,2
> limit 5;
>  date_started | symbol
> --+-
>  1970-01-01   | AADR.EU
>  1970-01-01   | AADR.IV
>  1970-01-01   | AADR.NV
>  1970-01-01   | AADR.SO
>  1970-01-01   | AADR.TC
>

Replica:

> =# select date_started, symbol from raw.symbols_aggregates order by 1,2
> limit 5;
>  date_started |symbol
> --+--
>  1970-01-01   | /EPRH18:XMON
>  1970-01-01   | /EPRM18:XMON
>  1970-01-01   | /FCEF18:XMON
>  1970-01-01   | /FCEG18:XMON
>  1970-01-01   | /FCEH18:XMON



On Wed, Jun 13, 2018 at 10:38 PM Tom Lane  wrote:

> Andrey Lizenko  writes:
> > I'm observing strange behaviour on comparing ::text field with string
> while
> > quering replica.
>
> These symptoms seem consistent with the theory that the replica's index
> for that column (symbols_aggregates_uniq) is corrupt.  I think your
> casts etc are just serving to defeat selection of an indexscan.
>
> Why it's corrupt, I dunno, but you might try forcing a reindex on the
> master.
>
> regards, tom lane
>


-- 
Regards, Andrei Lizenko