```
"pagelinks pl_namespace index-uniqueness-mismatch": {
"s3": [
"db1123.eqiad.wmnet",
"db1112.eqiad.wmnet",
"db1078.eqiad.wmnet",
"db1075.eqiad.wmnet"
```
Looks like some wikis on some hosts have this schema on `pagelinks` table:
```
CREATE TABLE `pagelinks` (
`pl_from` int(10) unsigned NOT NULL DEFAULT '0',
`pl_namespace` int(11) NOT NULL DEFAULT '0',
`pl_title` varbinary(255) NOT NULL DEFAULT '',
`pl_from_namespace` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`pl_from`,`pl_namespace`,`pl_title`),
UNIQUE KEY `pl_namespace` (`pl_namespace`,`pl_title`,`pl_from`),
KEY `pl_backlinks_namespace` (`pl_from_namespace`,`pl_namespace`,`pl_title`,`pl_from`)
) ENGINE=InnoDB DEFAULT CHARSET=binary ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8
```
The code looks like:
```
-- Reverse index, for Special:Whatlinkshere
CREATE INDEX /*i*/pl_namespace ON /*_*/pagelinks (pl_namespace,pl_title,pl_from);
-- Index for Special:Whatlinkshere with namespace filter
CREATE INDEX /*i*/pl_backlinks_namespace ON /*_*/pagelinks (pl_from_namespace,pl_namespace,pl_title,pl_from);
```
The alter needed:
```
alter table pagelinks drop key pl_namespace, add key pl_namespace (pl_namespace,pl_title,pl_from);
```
Schema change progress
[] eqiad
[x] codfw