Date: Tue, 2 Apr 2024 14:01:44 +0200
From: Erik Wienhold <ewie@ewie.name>
To: sud <suds1434@gmail.com>
Cc: pgsql-general <pgsql-general@lists.postgresql.org>
Subject: Re: Timestamp conversion Error in dynamic sql script
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On 2024-04-02 07:38 +0200, sud wrote:
> I am trying to create a block which will create a few partitions
> dynamically and also insert ~1million rows into each of those partitions.
> Not able to figure out why it's giving below error during timezone
> conversion while defining the partitions even though I used the typecast?
> 
> CREATE TABLE parent_table (
> id Numeric,
> col1 TEXT,
> col2 TEXT,
> partition_key TIMESTAMP,
> primary key (partition_key, id)
> )
> PARTITION BY RANGE (partition_key);
> 
> **********
> 
> DO $$
> DECLARE
> start_date TIMESTAMP := '2022-01-01';
> begin
> FOR i IN 0..10 LOOP
> 
> EXECUTE format('
>     CREATE TABLE parent_table_%s (
>         CHECK (partition_key >= DATE ''%s'' AND partition_key < DATE ''%s''
> )
>     ) INHERITS (parent_table);',
>     TO_CHAR(start_date + i, 'YYYY_MM_DD'),
> 
>     TO_CHAR(start_date + i, 'YYYY-MM-DD')::timestamp ,
>     TO_CHAR(start_date + i + INTERVAL '1 day', 'YYYY-MM-DD')::timestamp
> );
> EXECUTE format('
> ALTER TABLE parent_table ATTACH PARTITION parent_table_%s
> FOR VALUES FROM (''%s'') TO (''%s'');',
> TO_CHAR(start_date + i, 'YYYY_MM_DD'),
> TO_CHAR(start_date + i, 'YYYY-MM-DD')::timestamp,
> TO_CHAR(start_date + i + INTERVAL '1 day', 'YYYY-MM-DD') ::timestamp
> );
> 
> END LOOP;
> 
>   FOR i IN 0..10 LOOP
>     EXECUTE format('
>         INSERT INTO parent_table_%s (id,col1, col2,  partition_key)
>         SELECT
>             generate_series(1, 1000000),
>             md5(random()::text),
>             md5(random()::text),
>             TIMESTAMP ''%s'' + INTERVAL ''%s days''
>         FROM generate_series(1, 1000000);',
>         TO_CHAR(start_date + i, 'YYYY_MM_DD'),
>         start_date,
>         i
>     );
> END LOOP;
> END $$;
> 
> ***********
> 
> 
> 
> 
> *SQL Error [42883]: ERROR: operator does not exist: timestamp without time
> zone + integerHint: No operator matches the given name and argument types.
> You might need to add explicit type casts.Where: PL/pgSQL function
> inline_code_block line 7 at EXECUTEError position:*

Two ways to fix it:

1. Declare start_date as DATE when you want to add days with date + int

2. Keep TIMESTAMP and use start_date + make_interval(days => i)

-- 
Erik