@Override public Void run(TransactionContext transaction) throws SpannerException { client.singleUseReadOnlyTransaction(); return null; } });
@Override public Void run(TransactionContext transaction) throws SpannerException { client.singleUseReadOnlyTransaction(); return null; } });
/** Example of single use read only transaction. */ // [TARGET singleUseReadOnlyTransaction()] // [VARIABLE my_singer_id] public Timestamp singleUseReadOnlyTransaction(long singerId) { // [START singleUseReadOnlyTransaction] String column = "FirstName"; ReadOnlyTransaction txn = dbClient.singleUseReadOnlyTransaction(); Struct row = txn.readRow("Singers", Key.of(singerId), Collections.singleton(column)); row.getString(column); Timestamp timestamp = txn.getReadTimestamp(); // [END singleUseReadOnlyTransaction] return timestamp; }
/** Example of single use read only transaction with timestamp bound. */ // [TARGET singleUseReadOnlyTransaction(TimestampBound)] // [VARIABLE my_singer_id] public Timestamp singleUseReadOnlyTransactionTimestamp(long singerId) { // [START singleUseReadOnlyTransactionTimestamp] String column = "FirstName"; ReadOnlyTransaction txn = dbClient.singleUseReadOnlyTransaction(TimestampBound.ofMaxStaleness(10, TimeUnit.SECONDS)); Struct row = txn.readRow("Singers", Key.of(singerId), Collections.singleton(column)); row.getString(column); Timestamp timestamp = txn.getReadTimestamp(); // [END singleUseReadOnlyTransactionTimestamp] return timestamp; }
@Test public void singleStrong() { History expected = history.get(history.size() - 1); ReadOnlyTransaction readContext = client.singleUseReadOnlyTransaction(); Struct row = readRow(readContext); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); assertThat(readContext.getReadTimestamp()).isAtLeast(expected.timestamp); row = readRow(client.singleUse()); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); }
@Test public void singleMaxStaleness() { History minimum = history.get(2); NavigableMap<Timestamp, String> possibleValues = new TreeMap<>(); for (History item : history.subList(2, history.size())) { possibleValues.put(item.timestamp, item.value); } // Pick a staleness that cannot precede the second write (which, in practice, is the staleness // that exceeds the minimum commit time for the subsequent write). long stalenessNanos = System.nanoTime() - history.get(3).minCommitNanoTime; TimestampBound bound = TimestampBound.ofMaxStaleness(stalenessNanos, TimeUnit.NANOSECONDS); ReadOnlyTransaction readContext = client.singleUseReadOnlyTransaction(bound); Struct row = readRow(readContext); assertThat(row).isNotNull(); assertThat(readContext.getReadTimestamp()).isAtLeast(minimum.timestamp); assertThat(row.getString(0)) .isEqualTo(possibleValues.floorEntry(readContext.getReadTimestamp()).getValue()); row = readRow(client.singleUse(bound)); assertThat(row).isNotNull(); assertThat(row.getString(0)).isIn(possibleValues.values()); }
@Test public void singleMinReadTimestamp() { int minimumIndex = 2; History minimum = history.get(minimumIndex); NavigableMap<Timestamp, String> possibleValues = new TreeMap<>(); for (History item : history.subList(minimumIndex, history.size())) { possibleValues.put(item.timestamp, item.value); } TimestampBound bound = TimestampBound.ofMinReadTimestamp(minimum.timestamp); ReadOnlyTransaction readContext = client.singleUseReadOnlyTransaction(bound); Struct row = readRow(readContext); assertThat(row).isNotNull(); assertThat(readContext.getReadTimestamp()).isAtLeast(minimum.timestamp); assertThat(row.getString(0)) .isEqualTo(possibleValues.floorEntry(readContext.getReadTimestamp()).getValue()); row = readRow(client.singleUse(bound)); assertThat(row).isNotNull(); assertThat(row.getString(0)).isIn(possibleValues.values()); }
@Test public void singleExactStaleness() { // TODO(user): Use a shorter deadline (when supported) and pass on the call to Cloud Spanner. long deadlineNanoTime = System.nanoTime() + TimeUnit.MINUTES.toNanos(1); // The only exact staleness values that can be tested reliably are before the first item or // later than the last item: we choose the former. // // Pick a staleness that is "guaranteed" not to observe the first write. Note that this // guarantee doesn't strictly hold in the absence of enforced read deadlines, but we use a // deadline large enough to make it practically true. long stalenessNanos = 1 + deadlineNanoTime - history.get(0).minCommitNanoTime; TimestampBound bound = TimestampBound.ofExactStaleness(stalenessNanos, TimeUnit.NANOSECONDS); ReadOnlyTransaction readContext = client.singleUseReadOnlyTransaction(bound); Struct row = readRow(readContext); assertThat(row).isNull(); assertThat(readContext.getReadTimestamp().toSqlTimestamp()) .isLessThan(history.get(0).timestamp.toSqlTimestamp()); row = readRow(client.singleUse(bound)); assertThat(row).isNull(); }
@Test public void singleReadTimestamp() { History expected = history.get(2); TimestampBound bound = TimestampBound.ofReadTimestamp(expected.timestamp); ReadOnlyTransaction readContext = client.singleUseReadOnlyTransaction(bound); Struct row = readRow(readContext); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); assertThat(readContext.getReadTimestamp()).isEqualTo(expected.timestamp); row = readRow(client.singleUse(bound)); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); }
@Test public void query() { // We don't exhaustively test query with all modes - the read tests give us enough confidence // that transaction options are generated appropriately. Just do one test for each type of // context to ensure that transaction options are set at all. History expected = history.get(2); TimestampBound bound = TimestampBound.ofReadTimestamp(expected.timestamp); ReadOnlyTransaction readContext = client.singleUseReadOnlyTransaction(bound); Struct row = queryRow(readContext); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); assertThat(readContext.getReadTimestamp()).isEqualTo(expected.timestamp); readContext = client.readOnlyTransaction(bound); row = queryRow(readContext); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); assertThat(readContext.getReadTimestamp()).isEqualTo(expected.timestamp); readContext.close(); row = queryRow(client.singleUse(bound)); assertThat(row).isNotNull(); assertThat(row.getString(0)).isEqualTo(expected.value); }