Re: drop and recreate index in mysql DB

[Rick James]

Short answer:

CREATE table with all the indexes and don't worry about them.

Long answer:

* If you are loading one row at a time (that is a million INSERTs) into an existing table, have the indexes in place all the time.

* If you are _initially_ loading a table, and nothing else is going on other than loading the table, it _may_ be faster to have the PRIMARY KEY and FOREIGN KEYs in place, but add the secondary keys later.

* If you turn off / DROP an index, do some loading, then turn on / CREATE the index(es), that is bad if you are also accessing the table at the same time.

* If practical, use LOAD DATA with a million-row file. This will perform the load in the fastest(?) possible way.

Unrelated comments:

* Why is there a `prd01` and `prd01_stg`? They have the same schema?

* `prd01` -- does this mean that there is a `prd02`, `prd03`, etc? Yuck!

* Why are almost all the columns NULL? That seems unrealistic.

* I see 3 sets of code+type+name fields -- "arrays" usually should be be implemented as multiple columns; instead have another table. Ditto for ca_1/2/3.