Repository: kudu Updated Branches: refs/heads/master 030630ac0 -> 5360339df
KUDU-16: python client support for limits This patch allows python client users to impose a limit on the number of rows returned by a single scanner. Change-Id: I49e24ff45c7dd359b400e4270fe7573305075b39 Reviewed-on: http://gerrit.cloudera.org:8080/9924 Reviewed-by: Todd Lipcon <t...@apache.org> Tested-by: Kudu Jenkins Project: http://git-wip-us.apache.org/repos/asf/kudu/repo Commit: http://git-wip-us.apache.org/repos/asf/kudu/commit/5360339d Tree: http://git-wip-us.apache.org/repos/asf/kudu/tree/5360339d Diff: http://git-wip-us.apache.org/repos/asf/kudu/diff/5360339d Branch: refs/heads/master Commit: 5360339df6d2e6e0a143dfab2ea971c91d3af143 Parents: 030630a Author: Andrew Wong <anjuw...@g.ucla.edu> Authored: Tue Apr 3 23:50:40 2018 -0700 Committer: Grant Henke <granthe...@apache.org> Committed: Thu Apr 5 14:04:24 2018 +0000 ---------------------------------------------------------------------- python/kudu/client.pyx | 17 +++++++++++++++++ python/kudu/libkudu_client.pxd | 1 + python/kudu/tests/test_scanner.py | 9 +++++++++ 3 files changed, 27 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/kudu/blob/5360339d/python/kudu/client.pyx ---------------------------------------------------------------------- diff --git a/python/kudu/client.pyx b/python/kudu/client.pyx index ab43851..2be2c83 100644 --- a/python/kudu/client.pyx +++ b/python/kudu/client.pyx @@ -1623,6 +1623,23 @@ cdef class Scanner: return self + def set_limit(self, limit): + """ + Set a limit on the number of rows returned by this scanner. + Must be a positive value. + + Parameters + ---------- + limit : the maximum number of rows to return + + Returns + ------- + self : Scanner + """ + if limit <= 0: + raise ValueError("Limit must be positive.") + check_status(self.scanner.SetLimit(<int64_t> limit)) + def set_fault_tolerant(self): """ Makes the underlying KuduScanner fault tolerant. http://git-wip-us.apache.org/repos/asf/kudu/blob/5360339d/python/kudu/libkudu_client.pxd ---------------------------------------------------------------------- diff --git a/python/kudu/libkudu_client.pxd b/python/kudu/libkudu_client.pxd index e2bc90d..83cda7d 100644 --- a/python/kudu/libkudu_client.pxd +++ b/python/kudu/libkudu_client.pxd @@ -678,6 +678,7 @@ cdef extern from "kudu/client/client.h" namespace "kudu::client" nogil: Status SetFaultTolerant() Status AddLowerBound(const KuduPartialRow& key) Status AddExclusiveUpperBound(const KuduPartialRow& key) + Status SetLimit(int64_t limit) Status KeepAlive() Status GetCurrentServer(KuduTabletServer** server) http://git-wip-us.apache.org/repos/asf/kudu/blob/5360339d/python/kudu/tests/test_scanner.py ---------------------------------------------------------------------- diff --git a/python/kudu/tests/test_scanner.py b/python/kudu/tests/test_scanner.py index 23d5462..83e1193 100644 --- a/python/kudu/tests/test_scanner.py +++ b/python/kudu/tests/test_scanner.py @@ -59,6 +59,15 @@ class TestScanner(TestScanBase): tuples = _read_predicates(preds) self.assertEqual(sorted(tuples), self.tuples[20:50]) + def test_scan_limit(self): + # Set limits both below and above the max number of rows. + limits = [self.nrows - 1, self.nrows, self.nrows + 1] + for limit in limits: + scanner = self.table.scanner() + scanner.set_limit(limit) + tuples = scanner.read_all_tuples() + self.assertEqual(len(tuples), min(limit, self.nrows)) + def test_scan_rows_string_predicate_and_projection(self): scanner = self.table.scanner() scanner.set_projected_column_names(['key', 'string_val'])
