Combining postgres query and log duration

Question

I am aware that you can show the duration and log queries using the configuration below in postgresql.conf

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 CUSTOMIZED OPTIONS
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log_statement = 'all'
log_duration = on
log_line_prefix = '{"Time":[%t], Host:%h} '

And then returns logs like

{"Time":[2018-08-13 16:24:20 +08], Host:172.18.0.2} LOG:  statement: SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 1
{"Time":[2018-08-13 16:24:20 +08], Host:172.18.0.2} LOG:  duration: 7.694 ms

But can I combine the duration and statement in a single line like?

LOG: { statement: ..., duration: 7.694 ms}

Answer 1

The way you are logging, the statement is logged when the server starts processing it, but the duration is only known at the end of the execution.

This is why it has to be logged as two different messages.

If you use log_min_duration_statement = 0 instead, the statement is logged at the end of execution together with the duration.