DbIndex is a DbObject descendant describing a (secondary) index (normally, a bound to a DbTable).

Though omnipresent, indexes are completely vendor specific, they are not covered by any ANSI SQL section.

Nevertheless, most popular SQL dialects support statements like

CREATE           /* ...options... */ 
INDEX            /* ...options... */ 
${index.qName}   /* ...options... */ 
ON               /* ...options... */ 
${table.qName}   /* ...options... */ 
(${index.parts}) /* ...options... */

So, this class represent all components mentioned above, where all options are collected in one array. It's up to each DbLang descendant to distribute them properly.

Properties

Name	Type	Description	Notes
relation	DbRelation	Table, view etc. which this index belongs to	may be undefined
schemaName	String	Part of name from the beginning to the first '.' char, or null.	Normally, copied from relation
localName	String	The name of this index in its schema
qName	String	Quoted name of this index, good for SQL (DDL etc.)
parts	[String]	The list of expressions for the ON clause	mandatory; interpolated as is; typically, just column names
options	[String]	The list of global options for this index	[] by default
message	Error => String	Custom error message generator	For unique indexes

Sample fragment of a DbTable description file

    keys: {
        bad_idea :   null,                     // this index will be removed, if not yet
        label    :  'label',                   // like {parts: ['label']}
        priority : ['priority DESC', 'label'], // like {parts: ['priority DESC', 'label']}
        a_very_custom_index : {
//        localName :  ['ix_some_table_cust'],
          parts     :  ['SUBSTR(name, 1, 10) DESC NULLS FIRST'],
          options   :  [
            'UNIQUE',
            'USING BTREE',
            'WHERE priority = 10',
          ],
//        message : err => `You're so wrong: ${err.details}`,
        },
    },