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Best practices for schema management

Applies to: ✅ Microsoft FabricAzure Data Explorer

Here are several best practices to follow. They'll help make your management commands work better, and have a lighter impact on the service resources.

Action Use Don't use Notes
Create multiple tables Use a single .create tables command Don't issue many .create table commands
Rename multiple tables Make a single call to .rename tables Don't issue a separate call for each pair of tables
Show commands Use the lowest-scoped .show command Don't apply filters after a pipe (\|) Limit use as much as possible. When possible, cache the information they return.
Show extents Use .show table T extents Don't use .show cluster extents | where TableName == 'T'
Show database schema. Use .show database DB schema Don't use .show schema | where DatabaseName == 'DB'
Show large schema
Use .show databases schema Don't use .show schema For example, use on an environment with more than 100 databases.
Check a table's existence or get the table's schema Use .show table T schema as json Don't use .show table T Only use this command to get actual statistics on a single table.
Define the schema for a table that will include datetime values Set the relevant columns to the datetime type Don't convert string or numeric columns to datetime at query time for filtering, if that can be done before or during ingestion time
Add extent tag to metadata Use sparingly Avoid drop-by: tags, which limit the system's ability to do performance-oriented grooming processes in the background.
See performance notes.