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Parameter $table_name

Expected type: String
Description: The name of the table to add the index to

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Parameter $index_info

Expected type: Array
Description: An array of information about the index

Array Elements of $index_info
Key	Optional	Expected type	Description
columns	no	Array	An array of column names indicating which columns to add the index on
name	yes	String	The desired name of the index (not required for primary keys; if not set, SMF will choose the name)
type	yes	Enumerated String	What type of index this should be. Can be 'primary' (for primary key) or 'unique'. If not set, a regular index is created.

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Parameter $parameters

Expected type: Array
Description: An array of parameters

Array Elements of $parameters
Key	Optional	Expected type	Description
no_prefix	yes	Boolean	If true, SMF won't add the db_prefix to the table name

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Parameter $if_exists

Expected type: Enumerated String
Description: What to do if the index already exists. If set to an empty string, the function will return false if the index already exists.

Possible string values
Allowed values	Description
'update'	Remove the existing index with the given name and create a new one with the specified parameters

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Parameter $error

Expected type: Enumerated String
Description: Error parameter (currently not used?)

Possible string values
Allowed values	Description
'fatal'	Default value

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Return value

Expected type: Boolean
Description: True if the index was successfully added/updated, false if the index exists and "if_exists" isn't "update" or no columns are specified