Обсуждение: Error when rewriting a query into multiple queries

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Error when rewriting a query into multiple queries

От
"Huang Wang"
Дата:
Dear Sir or Madam,

I'm trying to add progressive query into Postgres. Assume a query 'SELECT * 
FROM hugetable', my idea is to rewrite it into several queries as
    'SELECT * FROM hugetable TABLESAMPLE SYSTEM_TIME(500)'
    'SELECT * FROM hugetable TABLESAMPLE SYSTEM_TIME(1000)'
    'SELECT * FROM hugetable TABLESAMPLE SYSTEM_TIME(1500)'
the first query will provide real-time results to the user and the following 
queries will return later for more accurate results. However, I got a 
'[42601]: ERROR: cannot insert multiple commands into a prepared statement' 
error after I modified postgres.c or parser.c. Is there any way to do it on 
the server or it's better to do it in the application? Thank you for your 
help.

Best regards,
Wang





Re: Error when rewriting a query into multiple queries

От
"David G. Johnston"
Дата:

On Friday, November 19, 2021, Huang Wang <hwang@rhrk.uni-kl.de> wrote:
Is there any way to do it on the server or it's better to do it in the application? 

Application; and for me at least modifying the server to do this is an extremely bad idea that goes against its fundamental design.

David J.