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Remove the recently added USE_SEGMENTED_FILES option, and indeed remove all

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support for a nonsegmented mode from md.c.  Per recent discussions, there
doesn't seem to be much value in a "never segment" option as opposed to
segmenting with a suitably large segment size.  So instead provide a
configure-time switch to set the desired segment size in units of gigabytes.
While at it, expose a configure switch for BLCKSZ as well.

Zdenek Kotala
This commit is contained in:
Tom Lane
2008-05-02 01:08:27 +00:00
parent 94b0b545f8
commit 3c6248a828
8 changed files with 223 additions and 170 deletions
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43
src/include/pg_config_manual.h
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@ -6,51 +6,10 @@
* for developers. If you edit any of these, be sure to do a *full*
* rebuild (and an initdb if noted).
*
* $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.31 2008/04/11 22:54:23 tgl Exp $
* $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.32 2008/05/02 01:08:27 tgl Exp $
*------------------------------------------------------------------------
*/
/*
* Size of a disk block --- this also limits the size of a tuple. You
* can set it bigger if you need bigger tuples (although TOAST should
* reduce the need to have large tuples, since fields can be spread
* across multiple tuples).
*
* BLCKSZ must be a power of 2. The maximum possible value of BLCKSZ
* is currently 2^15 (32768). This is determined by the 15-bit widths
* of the lp_off and lp_len fields in ItemIdData (see
* include/storage/itemid.h).
*
* Changing BLCKSZ requires an initdb.
*/
#define BLCKSZ 8192
/*
* RELSEG_SIZE is the maximum number of blocks allowed in one disk
* file when USE_SEGMENTED_FILES is defined. Thus, the maximum size
* of a single file is RELSEG_SIZE * BLCKSZ; relations bigger than that
* are divided into multiple files.
*
* RELSEG_SIZE * BLCKSZ must be less than your OS' limit on file size.
* This is often 2 GB or 4GB in a 32-bit operating system, unless you
* have large file support enabled. By default, we make the limit 1
* GB to avoid any possible integer-overflow problems within the OS.
* A limit smaller than necessary only means we divide a large
* relation into more chunks than necessary, so it seems best to err
* in the direction of a small limit. (Besides, a power-of-2 value
* saves a few cycles in md.c.)
*
* When not using segmented files, RELSEG_SIZE is set to zero so that
* this behavior can be distinguished in pg_control.
*
* Changing RELSEG_SIZE requires an initdb.
*/
#ifdef USE_SEGMENTED_FILES
#define RELSEG_SIZE (0x40000000 / BLCKSZ)
#else
#define RELSEG_SIZE 0
#endif
/*
* Size of a WAL file block. This need have no particular relation to BLCKSZ.
* XLOG_BLCKSZ must be a power of 2, and if your system supports O_DIRECT I/O,