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The Aerospike Query Operations provide the ability to query data in the Aerospike database. The queries can only be performed on secondary indexes, which have been created in the database. To scan all the records in the database, then you must use the Scan Operations.
Before you can execute a query, you first need to build a query using as_query. See as_query for details on building queries.
Once you have a query defined, then you can execute the query :
When aerospike_query_foreach() is executed, it will process the results and create records on the stack. Because the records are on the stack, they will only be available within the context of the callback function.
First, we define a query using as_query. The query will be for the "test" namespace and "demo" set. We will add a where predicate on "bin2", on which we have already created a secondary index.
Now that we have a query defined, we want to execute it using aerospike_query_foreach().
The callback provided to the function above is implemented as:
An as_query is simply a query definition, so it does not contain any state, allowing it to be reused for multiple query operations.
When you are finished with the query, you should destroy the resources allocated to it:
Typedefs | |
typedef bool(* | aerospike_query_foreach_callback )(const as_val *val, void *udata) |
Functions | |
as_status | aerospike_query_background (aerospike *as, as_error *err, const as_policy_write *policy, const as_query *query, uint64_t *query_id) |
as_status | aerospike_query_foreach (aerospike *as, as_error *err, const as_policy_query *policy, const as_query *query, aerospike_query_foreach_callback callback, void *udata) |
static as_status | aerospike_query_info (aerospike *as, as_error *err, const as_policy_info *policy, const as_query *query, uint64_t query_id, as_job_info *info) |
static as_status | aerospike_query_wait (aerospike *as, as_error *err, const as_policy_info *policy, const as_query *query, uint64_t query_id, uint32_t interval_ms) |
typedef bool(* aerospike_query_foreach_callback)(const as_val *val, void *udata) |
This callback will be called for each value or record returned from a query. Multiple threads will likely be calling this callback in parallel. Therefore, your callback implementation should be thread safe.
The aerospike_query_foreach() function accepts this callback.
val | The value received from the query. |
udata | User-data provided to the calling function. |
true
to continue to the next value. Otherwise, iteration will end. Definition at line 125 of file aerospike_query.h.
as_status aerospike_query_background | ( | aerospike * | as, |
as_error * | err, | ||
const as_policy_write * | policy, | ||
const as_query * | query, | ||
uint64_t * | query_id | ||
) |
Apply user defined function on records that match the query filter. Records are not returned to the client. This asynchronous server call will return before command is complete. The user can optionally wait for command completion.
as | The aerospike instance to use for this operation. |
err | The as_error to be populated if an error occurs. |
policy | The policy to use for this operation. If NULL, then the default policy will be used. |
query | The query to execute against the cluster. |
query_id | The id for the query job, which can be used for querying the status of the query. |
as_status aerospike_query_foreach | ( | aerospike * | as, |
as_error * | err, | ||
const as_policy_query * | policy, | ||
const as_query * | query, | ||
aerospike_query_foreach_callback | callback, | ||
void * | udata | ||
) |
Execute a query and call the callback function for each result item. Multiple threads will likely be calling the callback in parallel. Therefore, your callback implementation should be thread safe.
as | The aerospike instance to use for this operation. |
err | The as_error to be populated if an error occurs. |
policy | The policy to use for this operation. If NULL, then the default policy will be used. |
query | The query to execute against the cluster. |
callback | The callback function to call for each result value. |
udata | User-data to be passed to the callback. |
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inlinestatic |
Check the progress of a background query running on the database.
as | The aerospike instance to use for this operation. |
err | The as_error to be populated if an error occurs. |
policy | The info policy to use for this operation. If NULL, then the default policy will be used. |
query | The query that was executed against the cluster. |
query_id | The id for the query job, which can be used for querying the status of the query. |
info | Information about this background query, to be populated by this operation. |
Definition at line 246 of file aerospike_query.h.
References aerospike_job_info(), as_query_predicates::size, and as_query::where.
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inlinestatic |
Wait for a background query to be completed by servers.
as | The aerospike instance to use for this operation. |
err | The as_error to be populated if an error occurs. |
policy | The info policy to use for this operation. If NULL, then the default policy will be used. |
query | The query that was executed against the cluster. |
query_id | The id for the query job, which can be used for querying the status of the query. |
interval_ms | Polling interval in milliseconds. If zero, 1000 ms is used. |
Definition at line 222 of file aerospike_query.h.
References aerospike_job_wait(), as_query_predicates::size, and as_query::where.