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 a None set returns all the records in the namespace.

The scan is invoked using either foreach() or results(). The bins returned can be filtered using select().

See also

Scans and Managing Scans.

select(bin1[, bin2[, bin3..]])¶: Set a filter on the record bins resulting from results() or foreach(). 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 name 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 name 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 to Scan.results() and Scan.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 error AEROSPIKE_ERR_TIMEOUT.

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;

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 both socket_timeout and total_timeout are non-zero and socket_timeout > total_timeout, then socket_timeout will be set to total_timeout. If socket_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.

If total_timeout is not zero and total_timeout is reached before the transaction completes, the transaction will return error AEROSPIKE_ERR_TIMEOUT. If total_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 to Scan.foreach().

priority See Scan Constants for values. Default aerospike.SCAN_PRIORITY_AUTO.
nobins bool whether to return the bins portion of the Record Tuple. Default False.
concurrent bool whether to run the scan concurrently on all nodes of the cluster. Default False.
percent int percentage of records to return from the scan. Default 100.

New in version 1.0.39.

Scan Class — Scan¶

Scan¶

Scan Policies¶

Scan Options¶

Scan Class — `Scan`¶

`Scan`¶