[Postgres-xc-developers] Patch for pg_catalog-based views and pgadmin

[Mason S. <mas...@en...>]

I started the task to recognize more "Postgres-XC safe" queries.

I initially focused on native pg_catalog based views like pg_settings. 
This is because it used by pgadmin. With the attached patch, pgadmin no 
longer complains about such queries because they are now supported.

The PostgreSQL query rewriter appears to convert the view into a 
subquery. I modified the XC planner to check for pg_catalog table usage 
in the FROM clause (and subqueries thereof).

In addition, pgadmin was sending "SET client_encoding to 'UNICODE'". It 
was being swallowed and proxied by Postgres-XC, but no response was sent 
back because it did not recognize the 'S' message response. I have now 
added support for that, too.

Note that we have planned a whole separate task planned for proper SET 
handling. These commands will now be processed, but the user should not 
assume that these will remain set, due to Postgres-XC pooler. Again, we 
will address this in the future.

With this patch pgadmin runs much more smoothly when connected to 
Postgres-XC. Users can view schema information and issue SQL 
statements.  There is still an error window that pops up when clicking 
on a table because it issues a "SELECT count(*) FROM table", which is 
not yet supported in Postgres-XC. This problem will disappear soon 
however, as a patch is almost ready for basic aggregate support.

Thanks,

Mason


-- 
Mason Sharp
EnterpriseDB Corporation
The Enterprise Postgres Company


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