CREATE INDEX
- reference
The CREATE INDEX
statement allows you to create a secondary index.
Secondary indexes contain a filtered or a full set of keys in a given keyspace.
Secondary indexes are optional but increase query efficiency on a keyspace.
Purpose
In Couchbase Server 7.0 and later, CREATE INDEX
allows you to make multiple concurrent index creation requests.
The command starts a task to create the index definition in the background.
If there is an index creation task already running, the Index Service queues the incoming index creation request.
CREATE 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 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 secondary indexes on a keyspace and place them on separate nodes for better index availability.
In Couchbase Server Enterprise Edition, the recommended way to do this is using the num_replica
option.
In Couchbase Server Community Edition, you need to create multiple identical indexes and place them using the nodes
option.
Refer to WITH Clause below for more details.
Prerequisites
RBAC Privileges
User executing the CREATE INDEX statement must have the Query Manage Index privilege granted on the keyspace. For more details about user roles, see Authorization.
Syntax
create-index ::= 'CREATE' 'INDEX' index-name ( 'IF' 'NOT' 'EXISTS' )? 'ON' keyspace-ref
'(' index-key lead-key-attribs? ( ( ',' index-key key-attribs? )+ )? ')'
index-partition? where-clause? index-using? index-with?
- index-name
-
[Required] A unique name that identifies the index.
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.
- keyspace-ref
-
[Required] Specifies the keyspace where the index is created. Refer to Keyspace Reference below.
- index-key
-
[Required] Specifies an index key. Refer to Index Key below.
- lead-key-attribs
-
[Optional] Specifies attributes for the leading index key. Refer to Index Key Attributes below.
- key-attribs
-
[Optional] Specifies attributes for a non-leading index key. Refer to Index Key Attributes below.
- index-partition
-
[Optional] Specifies index partitions. Refer to PARTITION BY HASH Clause below.
- where-clause
-
[Optional] Specifies filters for a partial index. Refer to WHERE Clause 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 index already exists.
If an 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.
Index Key
index-key ::= expr | array-expr
Refers to an attribute name or a scalar function or an ARRAY expression on the attribute. This constitutes an index-key for the index.
- expr
-
A SQL++ expression over any fields in the document. This cannot use constant expressions, aggregate functions, or sub-queries.
- array-expr
-
An array expression. Array indexing enables you to create global indexes on array elements and optimize the execution of queries involving array elements. For details, refer to Array Indexing.
Index Key Attributes
lead-key-attribs ::= index-order include-missing? | include-missing index-order?
key-attribs ::= index-order
Specifies attributes for the index key.
- index-order
-
[Optional] All index keys may include an index order clause. Refer to Index Order below.
- include-missing
-
[Optional] The leading index key may also include
INCLUDE MISSING
clause. Refer to INCLUDE MISSING Clause below.
Index Order
index-order ::= 'ASC' | 'DESC'
Specifies the sort order of the index key.
ASC
-
The index key is sorted in ascending order.
DESC
-
The index key is sorted in descending order.
This clause is optional; if omitted, the default is ASC
.
INCLUDE MISSING Clause
include-missing ::= 'INCLUDE' 'MISSING'
The optional INCLUDE MISSING
clause ensures that documents which do not include the index key field are indexed regardless.
If this clause is not present, then documents without the index key field are not indexed.
The INCLUDE MISSING
clause can only be applied to the leading index key.
The INCLUDE MISSING
clause may be included before or after the ASC
or DESC
keyword.
PARTITION BY HASH Clause
Used to partition the index. Index partitioning helps increase the query performance by dividing and spreading a large index of documents across multiple nodes, horizontally scaling out an index as needed. For details, refer to Index Partitioning.
WHERE Clause
where-clause ::= 'WHERE' cond
- cond
-
Specifies WHERE clause predicates to qualify the subset of documents to include in the index.
USING Clause
index-using ::= 'USING' 'GSI'
In Couchbase Server 6.5 and later, the index type for a secondary 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.
A node name passed to the nodes
property must include the cluster administration port, by default 8091. For exampleWITH {"nodes": ["192.0.2.0:8091"]}
instead ofWITH {"nodes": ["192.0.2.0"]}
. - defer_build
-
[Optional] Boolean.
- true
-
When set to
true
, theCREATE 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 theBUILD INDEX
statement, multiple indexes to be built efficiently with one efficient scan of bucket data. - false
-
When set to
false
, theCREATE INDEX
operation queues the task for building the index and immediately kicks off the building of the index of type GSI.
- num_replica
Usage
It is not recommended to create (or drop) secondary indexes when any node with a secondary index role is down, as this may result in duplicate index names. |
Monitoring 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.
If the Index Service still cannot create the index after the maximum number of retries, the index state is marked as |
Using the meta().id
Function
You can create indexes on metadata information. For details, refer to Indexing Meta Info.
Using Indexes for Aggregates
If you have an index on a simple expression, such as geo.alt
, you can use that index to satisfy a query on an aggregate of that expression, such as MIN(geo.alt)
or MAX(geo.alt)
.
For details and examples, refer to Operator Pushdowns.
Index Replicas
In the Indexes screen in the Couchbase Web Console, index replicas are marked with their replica ID.
If you select view by server node
from the drop-down menu, you can see the server node where each index and index replica is placed.
You can also query the system:indexes catalog to find the ID of an index replica and see which node it is placed on.
By default, index replicas are used to serve index scans. The system automatically load-balances an index scan across the index and all its replicas. Adding index replicas enables you to scale scan throughput, in addition to providing high availability. |
Examples
To try the examples in this section, you must set the query context as described in each example.
For this example, unset the query context. For more information, see Query Context.
Create a secondary index that contains airports with an alt
value greater than 1000 on the node 127.0.0.1
.
CREATE INDEX idx_default_over1000
ON `travel-sample`(geo.alt)
WHERE geo.alt > 1000
USING GSI
WITH {"nodes": ["127.0.0.1:8091"]};
For this example, the path to the required keyspace is specified by the query, so you do not need to set the query context.
Create a secondary index that contains airports with an alt
value greater than 1000 on the node 127.0.0.1
.
CREATE INDEX idx_airport_over1000
ON `travel-sample`.inventory.airport(geo.alt)
WHERE geo.alt > 1000
USING GSI
WITH {"nodes": ["127.0.0.1:8091"]};
For this example, set the query context to the inventory
scope in the travel sample dataset.
For more information, see Query Context.
Create a secondary index with the defer_build
option.
CREATE INDEX idx_landmark_country
ON landmark(country)
USING GSI
WITH {"defer_build":true};
Query system:indexes
for the status of the index.
SELECT * FROM system:indexes WHERE name="idx_landmark_country";
[
{
"indexes": {
"bucket_id": "travel-sample",
"datastore_id": "http://127.0.0.1:8091",
"id": "d079aec40eb0c6cc",
"index_key": [
"`country`"
],
"keyspace_id": "landmark",
"name": "idx_landmark_country",
"namespace_id": "default",
"scope_id": "inventory",
"state": "deferred", (1)
"using": "gsi"
}
}
]
1 | Note that the index is in the deferred state. |
For this example, set the query context to the inventory
scope in the travel sample dataset.
For more information, see Query Context.
Kick off a deferred build using the index name.
BUILD INDEX ON landmark(idx_landmark_country) USING GSI;
Query system:indexes
for the status of the index.
SELECT * FROM system:indexes WHERE name="idx_landmark_country";
[
{
"indexes": {
"bucket_id": "travel-sample",
"datastore_id": "http://127.0.0.1:8091",
"id": "d079aec40eb0c6cc",
"index_key": [
"`country`"
],
"keyspace_id": "landmark",
"name": "idx_landmark_country",
"namespace_id": "default",
"scope_id": "inventory",
"state": "online", (1)
"using": "gsi"
}
}
]
1 | Note that the index has now been created. |
For this example, set the query context to the inventory
scope in the travel sample dataset.
For more information, see Query Context.
The following statement will not index airports where the district
field is missing.
CREATE INDEX idx_airport_missing
ON airport(district, name);
The following statement will index all airports, even if the district
field is not included in the document.
CREATE INDEX idx_airport_include
ON airport(district INCLUDE MISSING, name);
For more examples of indexes where the leading key may be missing, see Index Selection.