CREATE PRIMARY INDEX

Capella Operational

reference

The CREATE PRIMARY INDEX statement allows you to create a primary index. Primary indexes contain a full set of keys in a given keyspace. Primary indexes are optional and are only required for running ad hoc queries on a keyspace that is not supported by a secondary index.

Purpose

CREATE PRIMARY INDEX allows you to make multiple concurrent index creation requests. The command starts a task to create the primary index definition in the background. If there is an index creation task already running, the Index Service queues the incoming index creation request. CREATE PRIMARY INDEX returns as soon as the index creation phase is complete.

By default, when the index creation phase is complete, the Index Service triggers the index build phase. If you lose connectivity, the index build operation continues in the background. You can defer the index build phase using the defer_build clause. In deferred build mode, CREATE PRIMARY INDEX creates the index definition, but does not trigger the index build phase. You can then build the index using the BUILD INDEX command.

You can create multiple identical primary indexes on a keyspace and place them on separate nodes for better index availability. The recommended way to do this is using the num_replicas option. Refer to WITH Clause below for more details.

Prerequisites

RBAC Privileges

Users executing the CREATE PRIMARY INDEX statement must have the Query Manage Index privilege granted on the keyspace. For more details about user roles, see Authorization.

Syntax

create-primary-index ::= 'CREATE' 'PRIMARY' 'INDEX' index-name? ( 'IF' 'NOT' 'EXISTS' )?
                         'ON' keyspace-ref index-using? index-with?

index-name

[Optional] A unique name that identifies the index. If a name is not specified, the default name of #primary is applied.

Valid GSI index names can contain any of the following characters: A-Z a-z 0-9 # _, and must start with a letter, [A-Z a-z]. The minimum length of an index name is 1 character and there is no maximum length set for an index name. When querying, if the index name contains a # or _ character, you must enclose the index name within backticks.

Unnamed primary indexes are dropped by using the DROP PRIMARY INDEX statement, and named primary indexes are dropped by using the DROP INDEX statement.

keyspace-ref: [Required] Specifies the keyspace where the index is created. Refer to Keyspace Reference below.
index-using: [Optional] Specifies the index type. Refer to USING Clause below.
index-with: [Optional] Specifies options for the index. Refer to WITH Clause below.

IF NOT EXISTS Clause

The optional IF NOT EXISTS clause enables the statement to complete successfully when the specified primary index already exists. If a primary index with the same name already exists within the specified keyspace, then:

If this clause is not present, an error is generated.
If this clause is present, the statement does nothing and completes without error.

Keyspace Reference

keyspace-ref ::= keyspace-path | keyspace-partial

Specifies the keyspace for which the index needs to be created. The keyspace reference may be a keyspace path or a keyspace partial.

If there is a hyphen (-) inside any part of the keyspace reference, you must wrap that part of the keyspace reference in backticks (` `). Refer to the examples below.

Keyspace Path

keyspace-path ::= ( namespace ':' )? bucket ( '.' scope '.' collection )?

If the keyspace is a named collection, or the default collection in the default scope within a bucket, the keyspace reference may be a keyspace path. In this case, the query context should not be set.

namespace: (Optional) An identifier that refers to the namespace of the keyspace. Currently, only the default namespace is available. If the namespace name is omitted, the default namespace in the current session is used.
bucket: (Required) An identifier that refers to the bucket name of the keyspace.
scope: (Optional) An identifier that refers to the scope name of the keyspace. If omitted, the bucket’s default scope is used.
collection: (Optional) An identifier that refers to the collection name of the keyspace. If omitted, the default collection in the bucket’s default scope is used.

For example, default:`travel-sample` indicates the default collection in the default scope in the travel-sample bucket in the default namespace.

Similarly, default:`travel-sample`.inventory.airline indicates the airline collection in the inventory scope in the travel-sample bucket in the default namespace.

Keyspace Partial

keyspace-partial ::= collection

Alternatively, if the keyspace is a named collection, the keyspace reference may be just the collection name with no path. In this case, you must set the query context to indicate the required namespace, bucket, and scope.

collection: (Required) An identifier that refers to the collection name of the keyspace.

For example, airline indicates the airline collection, assuming the query context is set.

USING Clause

index-using ::= 'USING' 'GSI'

The index type for a primary index must be Global Secondary Index (GSI). The USING GSI keywords are optional and may be omitted.

WITH Clause

index-with ::= 'WITH' expr

Use the WITH clause to specify additional options.

expr

An object with the following properties:

nodes

[Optional] An array of strings, each of which represents a node name.

You can specify multiple nodes to distribute replicas of an index across nodes running the indexing service: for example, WITH {"nodes": ["node1:8091", "node2:8091", "node3:8091"]}. For details and examples, refer to Index Replication.

If specifying both nodes and num_replica, the number of nodes in the array must be one greater than the specified number of replicas otherwise the index creation will fail.

If nodes is not specified, then the system chooses nodes on which to place the new index and any replicas, in order to achieve the best resource utilization across nodes running the indexing service. This is done by taking into account the current resource usage statistics of index nodes.

A node name passed to the nodes property must include the cluster administration port, by default 8091. For example WITH {"nodes": ["192.0.2.0:8091"]} instead of WITH {"nodes": ["192.0.2.0"]}.

defer_build

[Optional] Boolean.

true: When set to true, the CREATE PRIMARY INDEX operation queues the task for building the index but immediately pauses the building of the index of type GSI. Index building requires an expensive scan operation. Deferring building of the index with multiple indexes can optimize the expensive scan operation. Admins can defer building multiple indexes and, using the BUILD INDEX statement, multiple indexes to be built efficiently with one efficient scan of keyspace data.
false: When set to false, the CREATE PRIMARY INDEX operation queues the task for building the index and immediately kicks off the building of the index of type GSI.

num_replica

[Optional] Integer that specifies the number of replicas of the index to create.

The indexer will automatically distribute these replicas amongst index nodes in the cluster for load-balancing and high availability purposes. The indexer will attempt to distribute the replicas based on the server groups in use in the cluster where possible.

If the value of this property is not less than the number of index nodes in the cluster, then the index creation will fail.

Usage

Monitoring Primary Indexes

Index metadata provides a state field. This state field and other index metadata can be queried using system:indexes. The index state may be scheduled for creation, deferred, building, pending, online, offline, or abridged. You can also monitor the index state using the Couchbase Web Console.

If you kick off multiple index creation operations concurrently, you may sometimes see transient errors similar to the following. If this error occurs, the Index Service tries to run the failed operation again in the background until it succeeds, up to a maximum of 1000 retries.

[
  {
    "code": 5000,
    "msg": "GSI CreateIndex() - cause: Encountered transient error.  Index creation will be retried in background.  Error: Index ... will retry building in the background for reason: Build Already In Progress. Keyspace ...",
    "query": "..."
  }
]

If the Index Service still cannot create the index after the maximum number of retries, the index state is marked as offline. You must drop the failed index using the DROP INDEX command.

Primary Scan Timeout

For a primary index scan on any keyspace size, the query engine guarantees that the client is not exposed to scan timeout if the indexer throws a scan timeout after it has returned a greater than zero sized subset of primary keys. To complete the scan, the query engine performs successive scans of the primary index until all the primary keys have been returned. It is possible that the indexer throws scan timeout without returning any primary keys, and in this event the query engine returns scan timeout to the client.

For example, if the indexer cannot find a snapshot that satisfies the consistency guarantee of the query within the timeout limit, it will timeout without returning any primary keys.

For secondary index scans, the query engine does not handle scan timeout, and returns index scan timeout error to the client. You can handle scan timeout on a secondary index by increasing the indexer timeout setting (see Query Settings) or preferably by defining and using a more selective index.

Examples

To try the examples in this section, you must set the query context as described in each example.

Example 1. Create a primary index in the default scope and collection

For this example, unset the query context. For more information, see Query Context.

Create a named primary index on the default collection in the default scope within the travel-sample bucket.

CREATE PRIMARY INDEX idx_default_primary ON `travel-sample` USING GSI;

Example 2. Create a primary index in a named scope and collection

For this example, the path to the required keyspace is specified by the query, so you do not need to set the query context.

This example is similar to Example 1, but creates a named primary index on the airport collection.

CREATE PRIMARY INDEX idx_airport_primary ON `travel-sample`.inventory.airport USING GSI;

Example 3. Create a deferred primary index

For this example, set the query context to the inventory scope in the travel sample dataset. For more information, see Query Context.

Create a named primary index using the defer_build option.

CREATE PRIMARY INDEX idx_hotel_primary
  ON hotel
  USING GSI
  WITH {"defer_build":true};

Query system:indexes for the status of the index.

SELECT * FROM system:indexes WHERE name="idx_hotel_primary";

The output from system:indexes shows the idx_hotel_primary in the deferred state.

Example 4. Build a deferred primary index

For this example, set the query context to the inventory scope in the travel sample dataset. For more information, see Query Context.

Kick off the deferred build on the named primary index.

BUILD INDEX ON hotel(idx_hotel_primary) USING GSI;

Query system:indexes for the status of the index.

SELECT * FROM system:indexes WHERE name="idx_hotel_primary";

The output from system:indexes shows that the index has now been created.