From cf6a9c3742a78414184a6e651e4cc7d239f8f2c4 Mon Sep 17 00:00:00 2001 From: Fujii Masao Date: Wed, 6 Aug 2014 14:49:43 +0900 Subject: [PATCH] Change ParseConfigFp() so that it doesn't process unused entry of each parameter. When more than one setting entries of same parameter exist in the configuration file, PostgreSQL uses only entry appearing last in configuration file scan. Since the other entries are not used, ParseConfigFp() doesn't need to process them, but previously it did that. This problematic behavior caused the configuration file scan to detect invalid settings of unused entries (e.g., existence of multiple entries of PGC_POSTMASTER parameter) and log the messages complaining about them. This commit changes the configuration file scan so that it processes only last entry of each parameter. Note that when multiple entries of same parameter exist both in postgresql.conf and postgresql.auto.conf, unused entries in postgresql.conf are still processed only at postmaster startup. The problem has existed since old version, but a user is more likely to encounter it since 9.4 where ALTER SYSTEM command was introduced. So back-patch to 9.4. Amit Kapila, slightly modified by me. Per report from Christoph Berg. --- src/backend/utils/misc/guc-file.l | 34 +++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l index 7d301055dd..e6e11090ab 100644 --- a/src/backend/utils/misc/guc-file.l +++ b/src/backend/utils/misc/guc-file.l @@ -562,7 +562,9 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel, { char *opt_name = NULL; char *opt_value = NULL; - ConfigVariable *item; + ConfigVariable *item, + *cur_item = NULL, + *prev_item = NULL; if (token == GUC_EOL) /* empty or comment line */ continue; @@ -645,13 +647,41 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel, } else { - /* ordinary variable, append to list */ + /* + * ordinary variable, append to list. For multiple items of + * same parameter, retain only which comes later. + */ item = palloc(sizeof *item); item->name = opt_name; item->value = opt_value; item->filename = pstrdup(config_file); item->sourceline = ConfigFileLineno-1; item->next = NULL; + + /* Remove the existing item of same parameter from the list */ + for (cur_item = *head_p; cur_item; prev_item = cur_item, + cur_item = cur_item->next) + { + if (strcmp(item->name, cur_item->name) == 0) + { + if (prev_item == NULL) + *head_p = cur_item->next; + else + { + prev_item->next = cur_item->next; + /* + * On removing last item in list, we need to update tail + * to ensure that list will be maintianed. + */ + if (prev_item->next == NULL) + *tail_p = prev_item; + } + + pfree(cur_item); + break; + } + } + if (*head_p == NULL) *head_p = item; else -- 2.40.0