Horton

Re: Attempt to consolidate reading of XLOG page

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Antonin Houska <ah@cybertec.at>
Cc: Thomas Munro <thomas.munro@gmail.com>, Robert Haas <robertmhaas@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2019-09-24T19:50:51Z
Lists: pgsql-hackers 
On 2019-Sep-24, Antonin Houska wrote:

> Alvaro Herrera <alvherre@2ndquadrant.com> wrote:

> > If you don't have any strong dislikes for these changes, I'll push this
> > part and let you rebase the remains on top.
> 
> No objections here.

oK, pushed.  Please rebase the other parts.

I made one small adjustment: in read_local_xlog_page() there was one
*readTLI output parameter that was being changed to a local variable
plus later assigment to the output struct member; I changed the code to
continue to assign directly to the output variable instead.  There was
an error case in which the TLI was not assigned to; I suppose this
doesn't really change things (we don't examine the TLI in that case, do
we?), but it seemed dangerous to leave like that.

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

Commits

  1. Remove logical_read_local_xlog_page

  2. Refactor WAL file-reading code into WALRead()

  3. Rework WAL-reading supporting structs

  4. Make XLogReaderInvalReadState static

  5. Use pg_pread() and pg_pwrite() for data files and WAL.