Re: [patch] Proposal for \crosstabview in psql

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Daniel Verite <daniel(at)manitou-mail(dot)org>
Cc: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>
Subject: Re: [patch] Proposal for \crosstabview in psql
Date: 2016-04-07 22:55:17
Message-ID: 20160407225517.GA612264@alvherre.pgsql
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Daniel Verite wrote:

> > * In the "if (cont.cells[idx] != NULL && cont.cells[idx][0] != '\0')"
> > block (line 497 in the attached), can't we do the same thing by using
> > psprintf?
>
> In that block, we can't pass a cell contents as a valist and be done with
> that cell, because duplicates of (col value,row value) may happen
> at any iteration of the upper loop over PQntuples(results). Any cell really
> may need reallocation unpredictably until that loop is done, whereas
> psprintf starts by allocating a new buffer unconditionally, so it doesn't
> look
> to me like it could help to simplify that block.

I messed with that code some more, as it looked unnecessarily
complicated; please see attached and verify that it still behaves
sanely. This needs those regression tests you promised. I tested a few
cases and it seems good to me.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment Content-Type Size
psql-crosstabview-v16.patch text/x-diff 39.6 KB

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