Overhaul site_stats table

The site stats table holds a bunch of metric fields, two of which are of
data type "bigint unsigned", 3 are "bigint" (signed) and one is int
(signed).  Also the default values differ widely: It is 0 on the
"unsigned" fields and the "int" field, but -1 on the three others. This
patch makes all of this more consistent:

Set all fields (except the ss_row_id, which isn't changed) data type to
"bigint unsigned". Also set NULL as the default value for all those
fields. Obviously -1 isn't a possible default value any more. Also, 0
can easily be mistaken for a real value (e.g. ss_active_users=0 -->
"there is nobody active on this wiki"). NULL, by it's definition, is the
value of choice for a value to insert into fields of which we don't know
a correct value.

The respective patch files were tested locally against MySql, Sqlite,
Postgres and SQL Server 2016. Neither oracle nor the upgrade with
update.php was tested.

Bug: T56888
Change-Id: I7d42aae434852a56b6f8dd559d8a5f3bce416021

1 files changed, 35 insertions, 0 deletions

diff --git a/maintenance/sqlite/archives/patch-site_stats-modify.sql b/maintenance/sqlite/archives/patch-site_stats-modify.sql
new file mode 100644
index 000000000000..8d267a62f005
--- /dev/null
+++ b/maintenance/sqlite/archives/patch-site_stats-modify.sql
@@ -0,0 +1,35 @@
+DROP TABLE IF EXISTS /*_*/site_stats_tmp;
+
+-- Create the temporary table. The following part
+-- is copied & pasted from the changed tables.sql
+-- file besides having an other table name.
+CREATE TABLE /*_*/site_stats_tmp (
+  ss_row_id int unsigned NOT NULL PRIMARY KEY,
+  ss_total_edits bigint unsigned default NULL,
+  ss_good_articles bigint unsigned default NULL,
+  ss_total_pages bigint unsigned default NULL,
+  ss_users bigint unsigned default NULL,
+  ss_active_users bigint unsigned default NULL,
+  ss_images bigint unsigned default NULL
+) /*$wgDBTableOptions*/;
+
+-- Move the data from the old to the new table
+INSERT OR IGNORE INTO /*_*/site_stats_tmp (
+	ss_row_id,
+	ss_total_edits,
+	ss_good_articles,
+	ss_total_pages,
+	ss_active_users,
+	ss_images
+) SELECT
+	ss_row_id,
+	ss_total_edits,
+	ss_good_articles,
+	ss_total_pages,
+	ss_active_users,
+	ss_images
+FROM /*_*/site_stats;
+
+DROP TABLE /*_*/site_stats;
+
+ALTER TABLE /*_*/site_stats_tmp RENAME TO /*_*/site_stats;