.alter-merge table command:
- Secures data in existing columns
- Adds new columns,
docstring, and folder, to an existing table
- Must run in the context of a specific database that scopes the table name
- Requires Table Admin permission
DocString is free text that you can attach to a table/function/column describing the entity. This string is presented in various UX settings next to the entity names.
.alter-merge command incorrectly may lead to data loss.
.alter-merge has a counterpart, the
.alter table command that has similar functionality. For more information, see
table TableName (columnName:columnType, ...) [
= Documentation] [
Specify the table columns:
- Columns that don't exist and which you specify, are added at the end of the existing schema.
- If the passed schema doesn't contain some table columns, the columns won't be deleted.
- If you specify an existing column with a different type, the command will fail.
.show table [TableName] cslschema to get the existing column schema before you alter it.
How will the command affect the data?
- Existing data isn't physically modified by the command. Data in removed columns is ignored. Data in new columns is assumed to be null.
- Depending on how the cluster is configured, data ingestion might modify the table's column schema, even without user interaction. When you make changes to a table's column schema, ensure that ingestion won't add needed columns that the command will then remove.
.alter-merge table MyTable (ColumnX:string, ColumnY:int) .alter-merge table MyTable (ColumnX:string, ColumnY:int) with (docstring = "Some documentation", folder = "Folder1")