From 8d30337566a94b5b66b00d1cdff01ec1203a53a2 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 4 Aug 2007 21:53:00 +0000
Subject: [PATCH] Fix up bad layout of some comments (probably pg_indent's
fault), and improve grammar a tad. Per Greg Stark.
---
src/backend/utils/adt/pg_lzcompress.c | 32 +++++++++++++--------------
src/include/utils/pg_lzcompress.h | 20 +++++++++--------
2 files changed, 26 insertions(+), 26 deletions(-)
diff --git a/src/backend/utils/adt/pg_lzcompress.c b/src/backend/utils/adt/pg_lzcompress.c
index 085bc63e0dd..f843232ba64 100644
--- a/src/backend/utils/adt/pg_lzcompress.c
+++ b/src/backend/utils/adt/pg_lzcompress.c
@@ -166,7 +166,7 @@
*
* Copyright (c) 1999-2007, PostgreSQL Global Development Group
*
- * $PostgreSQL: pgsql/src/backend/utils/adt/pg_lzcompress.c,v 1.26 2007/04/06 04:21:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/pg_lzcompress.c,v 1.27 2007/08/04 21:53:00 tgl Exp $
* ----------
*/
#include "postgres.h"
@@ -211,29 +211,27 @@ typedef struct PGLZ_HistEntry
* ----------
*/
static const PGLZ_Strategy strategy_default_data = {
- 256, /* Data chunks smaller 256 bytes are not
- * compressed */
- 6144, /* Data chunks greater equal 6K force
- * compression */
- /* except compressed result is greater uncompressed data */
- 20, /* Compression rates below 20% mean fallback
- * to uncompressed */
- /* storage except compression is forced by previous parameter */
+ 256, /* Data chunks less than 256 bytes are not
+ * compressed */
+ 6144, /* Data chunks >= 6K force compression, unless
+ * compressed output is larger than input */
+ 20, /* Below 6K, compression rates below 20% mean
+ * fallback to uncompressed */
128, /* Stop history lookup if a match of 128 bytes
- * is found */
+ * is found */
10 /* Lower good match size by 10% at every
- * lookup loop iteration. */
+ * lookup loop iteration */
};
const PGLZ_Strategy * const PGLZ_strategy_default = &strategy_default_data;
static const PGLZ_Strategy strategy_always_data = {
- 0, /* Chunks of any size are compressed */
- 0, /* */
- 0, /* We want to save at least one single byte */
+ 0, /* Chunks of any size are compressed */
+ 0,
+ 0, /* It's enough to save one single byte */
128, /* Stop history lookup if a match of 128 bytes
- * is found */
- 6 /* Look harder for a good match. */
+ * is found */
+ 6 /* Look harder for a good match */
};
const PGLZ_Strategy * const PGLZ_strategy_always = &strategy_always_data;
@@ -511,7 +509,7 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest,
* If the strategy forbids compression (at all or if source chunk too
* small), fail.
*/
- if (strategy->match_size_good == 0 ||
+ if (strategy->match_size_good <= 0 ||
slen < strategy->min_input_size)
return false;
diff --git a/src/include/utils/pg_lzcompress.h b/src/include/utils/pg_lzcompress.h
index bed75d9af17..fdd9701ee0e 100644
--- a/src/include/utils/pg_lzcompress.h
+++ b/src/include/utils/pg_lzcompress.h
@@ -3,7 +3,7 @@
*
* Definitions for the builtin LZ compressor
*
- * $PostgreSQL: pgsql/src/include/utils/pg_lzcompress.h,v 1.14 2007/02/27 23:48:10 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/pg_lzcompress.h,v 1.15 2007/08/04 21:53:00 tgl Exp $
* ----------
*/
@@ -50,16 +50,18 @@ typedef struct PGLZ_Header
*
* min_input_size Minimum input data size to start compression.
*
- * force_input_size Input data size at which compressed storage is
- * forced even if the compression rate drops below
- * min_comp_rate (but not below 0).
- *
- * min_comp_rate Minimum compression rate (0-99%), the output
- * must be smaller than the input. If that isn't
+ * force_input_size Minimum input data size to force compression
+ * even if the compression rate drops below
+ * min_comp_rate. But in any case the output
+ * must be smaller than the input. If that isn't
* the case, the compressor will throw away its
* output and copy the original, uncompressed data
* to the output buffer.
*
+ * min_comp_rate Minimum compression rate (0-99%) to require for
+ * inputs smaller than force_input_size. If not
+ * achieved, the output will be uncompressed.
+ *
* match_size_good The initial GOOD match size when starting history
* lookup. When looking up the history to find a
* match that could be expressed as a tag, the
@@ -70,8 +72,8 @@ typedef struct PGLZ_Header
* longer the lookup takes, the smaller matches
* are considered good.
*
- * match_size_drop The percentage, match_size_good is lowered
- * at each history check. Allowed values are
+ * match_size_drop The percentage by which match_size_good is lowered
+ * after each history check. Allowed values are
* 0 (no change until end) to 100 (only check
* latest history entry at all).
* ----------
--
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