Query Class — Query
¶
Query
¶
The query object created by calling
aerospike.query()
is used for executing queries over a secondary index of a specified set (which can be omitted orNone
). For queries, theNone
set contains those records which are not part of any named set.The query can (optionally) be assigned one of the following
One of the
predicates
(between()
orequals()
) usingwhere()
.A query without a predicate will match all the records in the given set, similar to a
Scan
.The query is invoked using
foreach()
,results()
, orexecute_background()
The bins returned can be filtered by usingselect()
.If a list of write operations is added to the query with
add_ops()
, they will be applied to each record processed by the query. See available write operations at Seeaerospike_helpers
Finally, a stream UDF may be applied with
apply()
. It will aggregate results out of the records streaming back from the query.See also
Queries and Managing Queries.
Query Fields and Methods¶
- class aerospike.Query¶
Fields
- Fieldname max_records
int
Approximate number of records to return to client. This number is divided by the number of nodes involved in the scan. The actual number of records returned may be less than max_records if node record counts are small and unbalanced across nodes. Requires server version >= 6.0.0Default:
0
(No Limit).- Fieldname records_per_second
int
Limit the scan to process records at records_per_second. Requires server version >= 6.0.0Default:
0
(no limit).
Note
Version >= 5.0.0 Supports aerrospike expressions for results, foreach, and execute_background see aerospike_helpers.expressions package. Requires server version >= 5.2.0.
import aerospike from aerospike_helpers import expressions as exp from aerospike import exception as ex import sys import time config = {"hosts": [("127.0.0.1", 3000)]} client = aerospike.client(config).connect() # register udf try: client.udf_put( "/path/to/my_udf.lua" ) except ex.AerospikeError as e: print("Error: {0} [{1}]".format(e.msg, e.code)) client.close() sys.exit(1) # put records and apply udf try: keys = [("test", "demo", 1), ("test", "demo", 2), ("test", "demo", 3)] records = [{"number": 1}, {"number": 2}, {"number": 3}] for i in range(3): client.put(keys[i], records[i]) try: client.index_integer_create("test", "demo", "number", "test_demo_number_idx") except ex.IndexFoundError: pass query = client.query("test", "demo") query.apply("my_udf", "my_udf", ["number", 10]) # only affect records with "number" bin greater than 1 expr = exp.GT(exp.IntBin("number"), 1).compile() policy = {"expressions": expr} job_id = query.execute_background(policy) # wait for job to finish while True: response = client.job_info(job_id, aerospike.JOB_SCAN) print(response) if response["status"] != aerospike.JOB_STATUS_INPROGRESS: break time.sleep(0.25) records = client.get_many(keys) print(records) except ex.AerospikeError as e: print("Error: {0} [{1}]".format(e.msg, e.code)) sys.exit(1) finally: client.close() # EXPECTED OUTPUT: # [ # (('test', 'demo', 1, bytearray(b'\xb7\xf4\xb88\x89\xe2\xdag\xdeh>\x1d\xf6\x91\x9a\x1e\xac\xc4F\xc8')), {'gen': 2, 'ttl': 2591999}, {'number': 1}), # (('test', 'demo', 2, bytearray(b'\xaejQ_7\xdeJ\xda\xccD\x96\xe2\xda\x1f\xea\x84\x8c:\x92p')), {'gen': 12, 'ttl': 2591999}, {'number': 12}), # (('test', 'demo', 3, bytearray(b'\xb1\xa5`g\xf6\xd4\xa8\xa4D9\xd3\xafb\xbf\xf8ha\x01\x94\xcd')), {'gen': 13, 'ttl': 2591999}, {'number': 13}) # ]
# contents of my_udf.lua function my_udf(rec, bin, offset) info("my transform: %s", tostring(record.digest(rec))) rec[bin] = rec[bin] + offset aerospike:update(rec) end
Note
For a similar example using .results() see
aerospike.Scan.results()
.Methods
- select(bin1[, bin2[, bin3..]])¶
Set a filter on the record bins resulting from
results()
orforeach()
. If a selected bin does not exist in a record it will not appear in the bins portion of that record tuple.
- where(predicate)¶
Set a where predicate for the query, without which the query will behave similar to
aerospike.Scan
. The predicate is produced by one of theaerospike.predicates
methodsequals()
andbetween()
.- Parameters
predicate (tuple) – the
tuple()
produced by one of theaerospike.predicates
methods.
Note
Currently, you can assign at most one predicate to the query.
- results([,policy [, options]]) -> list of (key, meta, bins)¶
Buffer the records resulting from the query, and return them as a
list
of records.- Parameters
policy (dict) – optional Query Policies.
options (dict) – optional Query Options.
- Returns
a
list
of Record Tuple.
import aerospike from aerospike import predicates as p import pprint config = { 'hosts': [ ('127.0.0.1', 3000)]} client = aerospike.client(config).connect() pp = pprint.PrettyPrinter(indent=2) query = client.query('test', 'demo') query.select('name', 'age') # matched records return with the values of these bins # assuming there is a secondary index on the 'age' bin of test.demo query.where(p.equals('age', 40)) records = query.results( {'total_timeout':2000}) pp.pprint(records) client.close()
Note
As of client 7.0.0 and with server >= 6.0 results and the query policy “partition_filter” see Partition Objects can be used to specify which partitions/records results will query. See the example below.
# This is an example of querying partitions 1000 - 1003. import aerospike query = client.query("test", "demo") policy = { "partition_filter": { "begin": 1000, "count": 4 }, }
# NOTE that these will only be non 0 if there are records in partitions 1000 - 1003 # results will be the records in partitions 1000 - 1003 results = query.results(policy=policy)
- foreach(callback[, policy[, options]])¶
Invoke the callback function for each of the records streaming back from the query.
- Parameters
callback (callable) – the function to invoke for each record.
policy (dict) – optional Query Policies.
options (dict) – optional Query Options.
Note
A Record Tuple is passed as the argument to the callback function. If the query is using the “partition_filter” query policy the callback will recieve two arguments The first is a
int
representing partition id, the second is the same Record Tuple as a normal callback.import aerospike from aerospike import predicates as p import pprint config = { 'hosts': [ ('127.0.0.1', 3000)]} client = aerospike.client(config).connect() pp = pprint.PrettyPrinter(indent=2) query = client.query('test', 'demo') query.select('name', 'age') # matched records return with the values of these bins # assuming there is a secondary index on the 'age' bin of test.demo query.where(p.between('age', 20, 30)) names = [] def matched_names(record): key, metadata, bins = record pp.pprint(bins) names.append(bins['name']) query.foreach(matched_names, {'total_timeout':2000}) pp.pprint(names) client.close()
Note
To stop the stream return
False
from the callback function.import aerospike from aerospike import predicates as p config = { 'hosts': [ ('127.0.0.1',3000)]} client = aerospike.client(config).connect() def limit(lim, result): c = [0] # integers are immutable so a list (mutable) is used for the counter def key_add(record): key, metadata, bins = record if c[0] < lim: result.append(key) c[0] = c[0] + 1 else: return False return key_add query = client.query('test','user') query.where(p.between('age', 20, 30)) keys = [] query.foreach(limit(100, keys)) print(len(keys)) # this will be 100 if the number of matching records > 100 client.close()
Note
As of client 7.0.0 and with server >= 6.0 foreach and the query policy “partition_filter” see Partition Objects can be used to specify which partitions/records foreach will query. See the example below.
# This is an example of querying partitions 1000 - 1003. import aerospike partitions = [] def callback(part_id, input_tuple): print(part_id) partitions.append(part_id) query = client.query("test", "demo") policy = { "partition_filter": { "begin": 1000, "count": 4 }, } query.foreach(callback, policy) # NOTE that these will only be non 0 if there are records in partitions 1000 - 1003 # should be 4 print(len(partitions)) # should be [1000, 1001, 1002, 1003] print(partitions)
- apply(module, function[, arguments])¶
Aggregate the
results()
using a stream UDF. If no predicate is attached to theQuery
the stream UDF will aggregate over all the records in the specified set.- Parameters
module (str) – the name of the Lua module.
function (str) – the name of the Lua function within the module.
arguments (list) – optional arguments to pass to the function. NOTE: these arguments must be types supported by Aerospike See: supported data types. If you need to use an unsuported type, (e.g. set or tuple) you can use a serializer like pickle first.
- Returns
one of the supported types,
int
,str
,float
(double),list
,dict
(map),bytearray
(bytes),bool
.
See also
Note
Assume we registered the following Lua module with the cluster as stream_udf.lua using
aerospike.udf_put()
.local function having_ge_threshold(bin_having, ge_threshold) return function(rec) debug("group_count::thresh_filter: %s > %s ?", tostring(rec[bin_having]), tostring(ge_threshold)) if rec[bin_having] < ge_threshold then return false end return true end end local function count(group_by_bin) return function(group, rec) if rec[group_by_bin] then local bin_name = rec[group_by_bin] group[bin_name] = (group[bin_name] or 0) + 1 debug("group_count::count: bin %s has value %s which has the count of %s", tostring(bin_name), tostring(group[bin_name])) end return group end end local function add_values(val1, val2) return val1 + val2 end local function reduce_groups(a, b) return map.merge(a, b, add_values) end function group_count(stream, group_by_bin, bin_having, ge_threshold) if bin_having and ge_threshold then local myfilter = having_ge_threshold(bin_having, ge_threshold) return stream : filter(myfilter) : aggregate(map{}, count(group_by_bin)) : reduce(reduce_groups) else return stream : aggregate(map{}, count(group_by_bin)) : reduce(reduce_groups) end end
Find the first name distribution of users in their twenties using a query aggregation:
import aerospike from aerospike import predicates as p import pprint config = {'hosts': [('127.0.0.1', 3000)], 'lua': {'system_path':'/usr/local/aerospike/lua/', 'user_path':'/usr/local/aerospike/usr-lua/'}} client = aerospike.client(config).connect() pp = pprint.PrettyPrinter(indent=2) query = client.query('test', 'users') query.where(p.between('age', 20, 29)) query.apply('stream_udf', 'group_count', [ 'first_name' ]) names = query.results() # we expect a dict (map) whose keys are names, each with a count value pp.pprint(names) client.close()
With stream UDFs, the final reduce steps (which ties the results from the reducers of the cluster nodes) executes on the client-side. Explicitly setting the Lua
user_path
in the config helps the client find the local copy of the module containing the stream UDF. Thesystem_path
is constructed when the Python package is installed, and contains system modules such asaerospike.lua
,as.lua
, andstream_ops.lua
. The default value for the Luasystem_path
is/usr/local/aerospike/lua
.
- add_ops(ops)¶
Add a list of write ops to the query. When used with
Query.execute_background()
the query will perform the write ops on any records found. If no predicate is attached to the Query it will apply ops to all the records in the specified set.- Parameters
ops – list A list of write operations generated by the aerospike_helpers e.g. list_operations, map_operations, etc.
Note
Requires server version >= 4.7.0.
import aerospike from aerospike_helpers.operations import list_operations from aerospike_helpers.operations import operations query = client.query('test', 'demo') ops = [ operations.append(test_bin, 'val_to_append'), list_operations.list_remove_by_index(test_bin, list_index_to_remove, aerospike.LIST_RETURN_NONE) ] query.add_ops(ops) id = query.execute_background() client.close()
For a more comprehensive example, see using a list of write ops with
Query.execute_background()
.
- execute_background([policy])¶
Execute a record UDF or write operations on records found by the query in the background. This method returns before the query has completed. A UDF or a list of write operations must have been added to the query with
Query.apply()
orQuery.add_ops()
respectively.- Parameters
policy (dict) – optional Write Policies.
- Returns
a job ID that can be used with
aerospike.job_info()
to track the status of theaerospike.JOB_QUERY
, as it runs in the background.
# Using a record UDF import aerospike query = client.query('test', 'demo') query.apply('myudfs', 'myfunction', ['a', 1]) query_id = query.execute_background() # This id can be used to monitor the progress of the background query
# Using a list of write ops. import aerospike from aerospike import predicates from aerospike import exception as ex from aerospike_helpers.operations import list_operations import sys import time # Configure the client. config = {"hosts": [("127.0.0.1", 3000)]} # Create a client and connect it to the cluster. try: client = aerospike.client(config).connect() except ex.ClientError as e: print("Error: {0} [{1}]".format(e.msg, e.code)) sys.exit(1) TEST_NS = "test" TEST_SET = "demo" nested_list = [{"name": "John", "id": 100}, {"name": "Bill", "id": 200}] # Write the records. try: keys = [(TEST_NS, TEST_SET, i) for i in range(5)] for i, key in enumerate(keys): client.put(key, {"account_number": i, "members": nested_list}) except ex.RecordError as e: print("Error: {0} [{1}]".format(e.msg, e.code)) # EXAMPLE 1: Append a new account member to all accounts. try: new_member = {"name": "Cindy", "id": 300} ops = [list_operations.list_append("members", new_member)] query = client.query(TEST_NS, TEST_SET) query.add_ops(ops) id = query.execute_background() # allow for query to complete time.sleep(3) print("EXAMPLE 1") for i, key in enumerate(keys): _, _, bins = client.get(key) print(bins) except ex.ClientError as e: print("Error: {0} [{1}]".format(e.msg, e.code)) sys.exit(1) # EXAMPLE 2: Remove a member from a specific account using predicates. try: # Add index to the records for use with predex. client.index_integer_create( TEST_NS, TEST_SET, "account_number", "test_demo_account_number_idx" ) ops = [ list_operations.list_remove_by_index("members", 0, aerospike.LIST_RETURN_NONE) ] query = client.query(TEST_NS, TEST_SET) number_predicate = predicates.equals("account_number", 3) query.where(number_predicate) query.add_ops(ops) id = query.execute_background() # allow for query to complete time.sleep(3) print("EXAMPLE 2") for i, key in enumerate(keys): _, _, bins = client.get(key) print(bins) except ex.ClientError as e: print("Error: {0} [{1}]".format(e.msg, e.code)) sys.exit(1) # Cleanup and close the connection to the Aerospike cluster. for i, key in enumerate(keys): client.remove(key) client.index_remove(TEST_NS, "test_demo_account_number_idx") client.close() """ EXPECTED OUTPUT: EXAMPLE 1 {'account_number': 0, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 1, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 2, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 3, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 4, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} EXAMPLE 2 {'account_number': 0, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 1, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 2, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 3, 'members': [{'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} {'account_number': 4, 'members': [{'name': 'John', 'id': 100}, {'name': 'Bill', 'id': 200}, {'name': 'Cindy', 'id': 300}]} """
- paginate()¶
Makes a query instance a paginated query. Call this if you are using the max_records and you need to query data in pages.
Note
Calling .paginate() on a query instance causes it to save its partition state. This can be retrieved later using .get_partitions_status(). This can also been done by using the partition_filter policy.
# Query 3 pages of 1000 records each. import aerospike pages = 3 page_size = 1000 query = client.query('test', 'demo') query.max_records = 1000 query.paginate() # NOTE: The number of pages queried and records returned per page can differ # if record counts are small or unbalanced across nodes. for page in range(pages): records = query.results() print("got page: " + str(page)) if query.is_done(): print("all done") break # This id can be used to paginate queries.
- is_done()¶
If using query pagination, did the previous paginated or partition_filter query using this query instance return all records?
- Returns
A
bool
signifying whether this paginated query instance has returned all records.
import aerospike query = client.query('test', 'demo') query.max_records = 1000 query.paginate() records = query.results(policy=policy) if query.is_done(): print("all done") # This id can be used to monitor the progress of a paginated query.
- get_partitions_status()¶
Get this query instance’s partition status. That is which partitions have been queried and which have not. The returned value is a
dict
with partition id,int
, as keys andtuple
as values. If the query instance is not tracking its partitions, the returneddict
will be empty.Note
A query instance must have had .paginate() called on it, or been used with a partition filter, in order retrieve its partition status. If .paginate() was not called, or partition_filter was not used, the query instance will not save partition status.
- Returns
a
tuple
of form (id:int
, init: class`bool`, done: class`bool`, digest:bytearray
). See Partition Objects for more information.
# This is an example of resuming a query using partition status. import aerospike for i in range(15): key = ("test", "demo", i) bins = {"id": i} client.put(key, bins) records = [] resumed_records = [] def callback(input_tuple): record, _, _ = input_tuple if len(records) == 5: return False records.append(record) query = client.query("test", "demo") query.paginate() query.foreach(callback) # The first query should stop after 5 records. assert len(records) == 5 partition_status = query.get_partitions_status() def resume_callback(part_id, input_tuple): record, _, _ = input_tuple resumed_records.append(record) query_resume = client.query("test", "demo") policy = { "partition_filter": { "partition_status": partition_status }, } query_resume.foreach(resume_callback, policy) # should be 15 total_records = len(records) + len(resumed_records) print(total_records) # cleanup for i in range(15): key = ("test", "demo", i) client.remove(key)
Query Policies¶
- policy
A
dict
of optional query policies which are applicable toQuery.results()
andQuery.foreach()
. See Policy Options.- max_retries
int
- Maximum number of retries before aborting the current transaction. The initial attempt is not counted as a retry.If max_retries is exceeded, the transaction will return error
AEROSPIKE_ERR_TIMEOUT
.Default:0
Warning
: Database writes that are not idempotent (such as “add”) should not be retried because the write operation may be performed multiple times if the client timed out previous transaction attempts. It’s important to use a distinct write policy for non-idempotent writes which sets max_retries = 0;
- max_retries
- sleep_between_retries
int
- Milliseconds to sleep between retries. Enter
0
to skip sleep.Default:0
- sleep_between_retries
- socket_timeout
int
- Socket idle timeout in milliseconds when processing a database command.If socket_timeout is not
0
and the socket has been idle for at least socket_timeout, both max_retries and total_timeout are checked. If max_retries and total_timeout are not exceeded, the transaction is retried.If bothsocket_timeout
andtotal_timeout
are non-zero andsocket_timeout
>total_timeout
, thensocket_timeout
will be set tototal_timeout
. Ifsocket_timeout
is0
, there will be no socket idle limit.Default:30000
.
- socket_timeout
- total_timeout
int
- Total transaction timeout in milliseconds.The total_timeout is tracked on the client and sent to the server along with the transaction in the wire protocol. The client will most likely timeout first, but the server also has the capability to timeout the transaction.If
total_timeout
is not0
total_timeout
is reached before the transaction completes, the transaction will return errorAEROSPIKE_ERR_TIMEOUT
. Iftotal_timeout
is0
, there will be no total time limit.Default:0
- total_timeout
- compress (
bool
) - Compress client requests and server responses.Use zlib compression on write or batch read commands when the command buffer size is greater than 128 bytes. In addition, tell the server to compress it’s response on read commands. The server response compression threshold is also 128 bytes.This option will increase cpu and memory usage (for extra compressed buffers), but decrease the size of data sent over the network.Default:
False
- compress (
- deserialize
bool
- Should raw bytes representing a list or map be deserialized to a list or dictionary.Set to False for backup programs that just need access to raw bytes.Default:
True
- deserialize
- fail_on_cluster_change
bool
- Deprecated in 6.0.0. No longer has any effect..Terminate query if cluster is in migration state.Default
False
- fail_on_cluster_change
- short_query
bool
- Is query expected to return less than 100 records.If True, the server will optimize the query for a small record set.This field is ignored for aggregation queries, background queriesand server versions less than 6.0.0.Mututally exclusive with records_per_secondDefault:
False
- short_query
- expressions
list
- Compiled aerospike expressions
aerospike_helpers
used for filtering records within a transaction.Default: NoneNote
Requires Aerospike server version >= 5.2.
- expressions
- partition_filter
dict
- A dictionary of partition information used by the clientto perform partiton queries. Useful for resuming terminated queries andquerying particular partitons/records.See Partition Objects for more information.Default:
{}
(All partitions will be queried).Note
Requires Aerospike server version >= 6.0
- partition_filter
Query Options¶
- options
A
dict
of optional query options which are applicable toQuery.foreach()
andQuery.results()
.- nobins
bool
- nobins
New in version 3.0.0.