Scan Class — Scan
¶
Scan
¶
-
class
aerospike.
Scan
¶ The Scan object is used to return all the records in a specified set (which can be ommitted or
None
). A Scan with aNone
set returns all the records in the namespace.The scan is invoked using either
foreach()
orresults()
. The bins returned can be filtered usingselect()
.See also
Scans and Managing Scans.
-
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.
-
results
([policy[, nodename]]) -> list of (key, meta, bins)¶ Buffer the records resulting from the scan, and return them as a
list
of records.Parameters: - policy (dict) – optional Scan Policies.
- nodename (str) – optional Node ID of node used to limit the scan to a single node.
Returns: a
list
of Record Tuple.import aerospike import pprint pp = pprint.PrettyPrinter(indent=2) config = { 'hosts': [ ('127.0.0.1',3000)]} client = aerospike.client(config).connect() client.put(('test','test','key1'), {'id':1,'a':1}, policy={'key':aerospike.POLICY_KEY_SEND}) client.put(('test','test','key2'), {'id':2,'b':2}, policy={'key':aerospike.POLICY_KEY_SEND}) scan = client.scan('test', 'test') scan.select('id','a','zzz') res = scan.results() pp.pprint(res) client.close()
Note
We expect to see:
[ ( ( 'test', 'test', u'key2', bytearray(b'\xb2\x18\n\xd4\xce\xd8\xba:\x96s\xf5\x9ba\xf1j\xa7t\xeem\x01')), { 'gen': 52, 'ttl': 2592000}, { 'id': 2}), ( ( 'test', 'test', u'key1', bytearray(b'\x1cJ\xce\xa7\xd4Vj\xef+\xdf@W\xa5\xd8o\x8d:\xc9\xf4\xde')), { 'gen': 52, 'ttl': 2592000}, { 'a': 1, 'id': 1})]
-
foreach
(callback[, policy[, options[, nodename]]])¶ Invoke the callback function for each of the records streaming back from the scan.
Parameters: - callback (callable) – the function to invoke for each record.
- policy (dict) – optional Scan Policies.
- options (dict) – the Scan Options that will apply to the scan.
- nodename (str) – optional Node ID of node used to limit the scan to a single node.
Note
A Record Tuple is passed as the argument to the callback function.
import aerospike import pprint pp = pprint.PrettyPrinter(indent=2) config = { 'hosts': [ ('127.0.0.1',3000)]} client = aerospike.client(config).connect() client.put(('test','test','key1'), {'id':1,'a':1}, policy={'key':aerospike.POLICY_KEY_SEND}) client.put(('test','test','key2'), {'id':2,'b':2}, policy={'key':aerospike.POLICY_KEY_SEND}) def show_key((key, meta, bins)): print(key) scan = client.scan('test', 'test') scan_opts = { 'concurrent': True, 'nobins': True, 'priority': aerospike.SCAN_PRIORITY_MEDIUM } scan.foreach(show_key, options=scan_opts) client.close()
Note
We expect to see:
('test', 'test', u'key2', bytearray(b'\xb2\x18\n\xd4\xce\xd8\xba:\x96s\xf5\x9ba\xf1j\xa7t\xeem\x01')) ('test', 'test', u'key1', bytearray(b'\x1cJ\xce\xa7\xd4Vj\xef+\xdf@W\xa5\xd8o\x8d:\xc9\xf4\xde'))
Note
To stop the stream return
False
from the callback function.from __future__ import print_function import aerospike 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((key, metadata, bins)): if c[0] < lim: result.append(key) c[0] = c[0] + 1 else: return False return key_add scan = client.scan('test','user') keys = [] scan.foreach(limit(100, keys)) print(len(keys)) # this will be 100 if the number of matching records > 100 client.close()
-
Scan Policies¶
-
policy
A
dict
of optional scan policies which are applicable toScan.results()
andScan.foreach()
. See Policies.- max_retries
- An
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 errorAEROSPIKE_ERR_TIMEOUT
.WARNING: Database writes that are not idempotent (such as “add”) should not be retried because the write operation may be performed multiple timesif 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;Default:0
- sleep_between_retries
- An
int
. Milliseconds to sleep between retries. Enter zero to skip sleep. Default:0
- socket_timeout
- An
int
. Socket idle timeout in milliseconds when processing a database command.If socket_timeout is not zero 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
is zero, there will be no socket idle limit.Default:30000
.
- total_timeout
- An
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.Iftotal_timeout
is not zero andtotal_timeout
is reached before the transaction completes, the transaction will return errorAEROSPIKE_ERR_TIMEOUT
. Iftotal_timeout
is zero, there will be no total time limit.Default:0
fail_on_cluster_change
bool
: Abort the scan if the cluster is not in a stable state. Default:False
- durable_delete
- A
bool
: If the transaction results in a record deletion, leave a tombstone for the record.This prevents deleted records from reappearing after node failures.Valid for Aerospike Server Enterprise Edition only.Default:False
(do not tombstone deleted records).
Scan Options¶
-
options
A
dict
of optional scan options which are applicable toScan.foreach()
.- priority See Scan Constants for values. Default
aerospike.SCAN_PRIORITY_AUTO
. - nobins
bool
whether to return the bins portion of the Record Tuple. DefaultFalse
. - concurrent
bool
whether to run the scan concurrently on all nodes of the cluster. DefaultFalse
. - percent
int
percentage of records to return from the scan. Default100
.
New in version 1.0.39.
- priority See Scan Constants for values. Default