File Compability_note.txt of Package influxdb

You can no longer specify a different ORDER BY clause in a subquery than
the one in the top level query. This functionality never worked properly,
but was not explicitly forbidden.

As part of the ongoing development of the tsi1 index,
the implementation of a Bloom Filter, used to efficiently determine
if series are not present in the index, was altered in #8857. While
this significantly increases the performance of the index and reduce
its memory consumption, the existing tsi1 indexes created while
running previous versions of the database are not compatible with 1.4.0.

Users with databases using the tsi1 inde
must go through the following process to upgrade to 1.4.0:

    1. Stop influxd.
    2. Remove all index directories on databases using the tsi1 index.
       With default configuration these can be found in
       /var/lib/influxdb/data/DB_NAME/RP_NAME/SHARD_ID/index
       or ~/.influxdb/data/DB_NAME/RP_NAME/SHARD_ID/index.
       It's worth noting at this point how many different shard_ids you visit.
    3. Run the influx_inspect inmem2tsi tool using the shard's
       data and WAL directories for -datadir and -waldir, respectively.
       Given the example in step (2) that would be influx_inspect 
       inmem2tsi -datadir /var/lib/influxdb/data/DB_NAME/RP_NAME/SHARD_ID
       -waldir /path/to/influxdb/wal/DB_NAME/RP_NAME/SHARD_ID.
    4. Repeat step (3) for each shard that needs to be converted.
    5. Start influxd.

Users with existing tsi1 shards, who attempt to start version 1.4.0 without
following the above steps, will find the shards refuse to open,
and will most likely see the following error message:

incompatible tsi1 index MANIFEST