web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: query planner: documented how to prevent incorrect query plans (`SET enable_seqscan = off;`, etc.)

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: query planner: documented that incorrect query plans are an ongoing bug in Postgres, because it does not support index hints and by default does not follow the join order. specifically, Postgres often does the following things in query plans which should normally never be done:...

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added description of join_collapse_limit config param (which should be turned off, although it is on by default). added links for using TIDs ("the fastest possible access to a single row").

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added links for troubleshooting autovacuuming (which can slow queries down significantly when it isn't happening for any tables)

lib/Firefox_bookmarks.reformat.csv: "page's description": changed to "page's own description" to clarify that this is a description provided by the page itself

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added links for error reporting levels and how to hide stack traces in psql. SQL: added links for recursive queries, which can be used to traverse hierarchical (parent-pointer) tables.

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: difference between STABLE and IMMUTABLE: functions that depend on the search_path: clarified that the confusing effects of using IMMUTABLE for one of these functions are only noticeable if the function is called on only constant values in a PL/pgSQL function (in which case the wrong search_path (the one in effect at create time) will be used)

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added explanation of the difference between STABLE and IMMUTABLE, and common pitfalls in using IMMUTABLE when you should use STABLE. svn: added troubleshooting steps for running `svn upgrade` after the last Mac system update, which upgrades svn.

web/links/index.htm: updated to Firefox bookmarks: Roundtable: virtual collaboration: annotated the linked pages

web/links/index.htm: updated to Firefox bookmarks: Roundtable: added materials for virtual collaboration roundtable. Mac: added steps for customizing screen saver security settings beyond the options supported in the UI.