Re: When is the MessageContext released?

On 2019-02-27 14:08:47 +0800, Andy Fan wrote:
> Hi :
> I run a query like "select * from t" and set the break like this:
>
> break exec_simple_query
> break MemoryContextDelete
> commands
> p context->name
> c
> end
>
> I can see most of the MemoryContext is relased, but never MessageContext,
> when will it be released?

It's released above exec_simple_query, as it actually contains the data
that lead us to call exec_simple_query(). See the main for loop in
PostgresMain():

/*
* Release storage left over from prior query cycle, and create a new
* query input buffer in the cleared MessageContext.
*/
MemoryContextSwitchTo(MessageContext);
MemoryContextResetAndDeleteChildren(MessageContext);

Greetings,

Andres Freund