Dialect-Specific Features

Arrays of ENUMS

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This feature is only available in PostgreSQL

Array(Enum) type requires special treatment. Whenever Sequelize will talk to the database, it has to typecast array values with ENUM name.

So this enum name must follow this pattern enum_<table_name>_<col_name>. If you are using sync then correct name will automatically be generated.

Table Hints

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This feature is only available in MS SQL Server

The tableHint option can be used to define a table hint. The hint must be a value from TableHints and should only be used when absolutely necessary. Only a single table hint is currently supported per query.

Table hints override the default behavior of MSSQL query optimizer by specifying certain options. They only affect the table or view referenced in that clause.

import { TableHints } from '@sequelize/core';

Project.findAll({
  // adding the table hint NOLOCK
  tableHint: TableHints.NOLOCK,
  // this will generate the SQL 'WITH (NOLOCK)'
});

Index Hints

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This feature is only available in MySQL & MariaDB

The indexHints option can be used to define index hints. The hint type must be a value from IndexHints and the values should reference existing indexes.

Index hints override the default behavior of the MySQL query optimizer.

import { IndexHints } from '@sequelize/core';
Project.findAll({
  indexHints: [{ type: IndexHints.USE, values: ['index_project_on_name'] }],
  where: {
    id: {
      [Op.gt]: 623,
    },
    name: {
      [Op.like]: 'Foo %',
    },
  },
});

The above will generate a MySQL query that looks like this:

SELECT * FROM Project USE INDEX (index_project_on_name) WHERE name LIKE 'FOO %' AND id > 623;

IndexHints includes USE, FORCE, and IGNORE.

See Issue #9421 for the original API proposal.