Understanding the Reindexer Enable Settings
At the database level, you can enable or disable automatic reindexing by setting the reindexer enable setting to true or false for that database. When the reindexer is enabled, any index or fragment changes to the database settings will cause all documents in the database that are not indexed/fragmented according to the settings to initiate a reindex operation. Note the following about the database settings and the reindex operation:
When reindexing is enabled, the reindex operation runs as a background task. You can set a higher or lower priority on the reindexing task by increasing or decreasing the setting of the
reindexer throttle.Any new documents added to or updated in the database will get the new database settings. This is true both with reindexing enabled and with reindexing disabled.
After changing index or fragmentation settings in a database, because new or modified documents get the new settings, the database can get into a state where some documents are indexed/fragmented differently from other documents in the database.
After changing index or fragmentation settings in a database in which reindexing is enabled, the old documents are reindexed according to the new settings, but the new settings do not take effect for queries until the reindex operation has completed and all documents are indexed to the state matching the database settings.
After changing index or fragmentation settings in a database in which reindexing is disabled, new and changed documents get the current settings, but queries will not take advantage of the new settings until all documents in the database match the database settings.
Even if reindexing is disabled, when you add tokenizer overrides to a field, those tokenization changes take effect immediately, so all new queries against the field will use the new tokenization (even if it is indexed with the previous tokenization).