DESCRIBE INDEX Statement
The DESCRIBE INDEX statement defines the specified index on a table.
Syntax
describe_index_statement ::=
(DESCRIBE | DESC) [AS JSON] INDEX index_name ON table_name
Semantics
If you want the output to be in JSON format, you can specify the optional AS JSON.
The description for the index contains the following information:
- Name of the table on which the index is defined.
- Name of the index.
- Type of index. Whether the index is primary index or secondary index.
- Whether the index is multikey? If the index is multikey then 'Y' is displayed. Otherwise, 'N' is displayed.
- List of fields on which the index is defined.
- The declared type of the index.
- Description of the index.
Example 8-17
The following
statement provides information about the index idx_income1
on the
UserInfo
table.
DESCRIBE AS JSON INDEX idx_income1 ON UserInfo
Output:
{
"name" : "idx_income1",
"type" : "secondary",
"fields" : ["info.income"],
"types" : ["ANY_ATOMIC"],
"withNoNulls" : false,
"withUniqueKeysPerRow" : false
}
Example 8-18
The following
statement provides information about the index idx_phones
on the
UserInfo
table.
DESCRIBE AS JSON INDEX idx_phones ON UserInfo
Output:
{
"name" : "idx_phones",
"type" : "secondary",
"fields" : ["info.phones[].number"],
"types" : ["INTEGER"],
"withNoNulls" : false,
"withUniqueKeysPerRow" : true
}
Example 8-19
The following
statement provides information about the index idx_modtime
on the
users
table.
DESCRIBE AS JSON INDEX idx_modtime ON users
Output:
{
"name" : "idx_modtime",
"type" : "secondary",
"fields" : ["modification_time#"],
"withNoNulls" : false,
"withUniqueKeysPerRow" : false
}
Example 8-20
idx_showid_year_month
on the stream_acct
table. DESCRIBE AS JSON INDEX idx_showid_year_month ON stream_acct
Output:
{
"name" : "idx_showid_year_month",
"type" : "secondary",
"fields" : ["acct_data.contentStreamed[].showId", "substring#acct_data.contentStreamed[].seriesInfo[].episodes[].date@,0,4", "substring#acct_data.contentStreamed[].seriesInfo[].episodes[].date@,5,2"],
"types" : ["INTEGER", "STRING", "STRING"],
"withNoNulls" : false,
"withUniqueKeysPerRow" : false
}