MySQL Indexing Issues

Dr_Duru
Dr_Duru Member
in Magic ETL

When setting up Indexes in my SQL dataflow, I notice sometimes that a few columns in the join are not made available for indexing. Why is that? What can I do to fix this? I suspect without the indexing, my dataflow is taking an inordinate amount of time.

Also, in the Domo help on optimizing data flows with indexing, the following recommendation appears:

"You should index the two columns in the ON statement. There are two ways you can accomplish this.

  1. Adding a new SQL type transform BEFORE the transform where the join is happening.
  2. Using Easy Indexing you can quickly add an index on one or more columns right in your Table Transform without the use of SQL."

What does #1 mean?

#2 is where my problems are happening where some columns in the join are not available for indexing.

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Comments

  • trafalger
    trafalger Coach

    #1 is writing a SQL statement, like

    ALTER TABLE t1 ADD INDEX('t1.COLUMN')

  • Dr_Duru
    Dr_Duru Member

    @trafalger I see. Now I finally understand a use case for using the SQL transform in SQL data flows! Thanks.

  • jaeW_at_Onyx
    jaeW_at_Onyx Coach

    @trafalger I do wonder if you add the index in the UI if the data is indexed as it's being loaded into the table, or if if the index is added after CREATE TABLE AS SELECT ...

    So i i guess if you wanted to be REALLY fancy you would CREATE TABLE, ALTER TABLE and then load data... but then the table doesn't appear in the UI.

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