Re: Beta 1.6: Output Headers refresh in slow motion

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From: Harald Armin Massa [mailto:haraldarminmassa(at)gmail(dot)com]
Sent: 15 September 2006 16:57
To: Dave Page
Cc: pgadmin-support(at)postgresql(dot)org
Subject: Re: [pgadmin-support] Beta 1.6: Output Headers refresh
in slow motion

Same "slow motion" is happening on resizing the output
pane panel.

What's happening is that when the grid control redraws
itself, it asks the dataset what the header labels should be. The
dataset then queries the database to get the correct typename (because
libpq's PGresult only stores the type OIDs) for each column.

Hmmm.... isn't the relation type OID -> type fixed for every
given instance of a database?
Maybe it would be even quicker to have a local cache of

typeOID -> typeName

So even new queries will get their column headers quick

Aside from the non-trivial architectural changes this would require,
there are also cache invalidation issues to consider - one instance of
pgAdmin can use multiple connections to the same database, each of which
would need it's own cache and even tracking and invalidating them would
be difficult, never mind changes from other developers (in fact, they
would require at least one query per cache access to check for changes
anyway).

Maybe something could be could be done for 1.8, but not for 1.6.

>I've committed a fix that will cache the type names as they are
requested so that after the >initial display, subsequent redraws won't
cause any queries to be sent to the backend.

Thats fine.

Of course, this behaviour doesn't show up on a fast PC
running the server on localhost :-)

Aaaah... now I know why with at 1600 (4pm) that redraw grew
faster ... most people left the office, so the WAN was more responsive
:)

:-)

Regards, Dave .