Manual:$wgTemplateLinksSchemaMigrationStage/en

Details
table schema migration stage, for normalizing and  fields.

Use the  flags. Supported values:


 * SCHEMA_COMPAT_OLD
 * SCHEMA_COMPAT_WRITE_BOTH | SCHEMA_COMPAT_READ_OLD
 * SCHEMA_COMPAT_WRITE_BOTH | SCHEMA_COMPAT_READ_NEW
 * SCHEMA_COMPAT_NEW