| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.cassandra.db.view; |
| |
| import java.nio.ByteBuffer; |
| import java.util.*; |
| |
| import com.google.common.collect.Iterators; |
| import com.google.common.collect.PeekingIterator; |
| |
| import org.apache.cassandra.config.CFMetaData; |
| import org.apache.cassandra.config.ColumnDefinition; |
| import org.apache.cassandra.config.ViewDefinition; |
| import org.apache.cassandra.db.*; |
| import org.apache.cassandra.db.rows.*; |
| import org.apache.cassandra.db.partitions.*; |
| import org.apache.cassandra.db.marshal.AbstractType; |
| import org.apache.cassandra.db.marshal.CompositeType; |
| |
| /** |
| * Creates the updates to apply to a view given the existing rows in the base |
| * table and the updates that we're applying to them (this handles updates |
| * on a single partition only). |
| * |
| * This class is used by passing the updates made to the base table to |
| * {@link #addBaseTableUpdate} and calling {@link #generateViewUpdates} once all updates have |
| * been handled to get the resulting view mutations. |
| */ |
| public class ViewUpdateGenerator |
| { |
| private final View view; |
| private final int nowInSec; |
| |
| private final CFMetaData baseMetadata; |
| private final DecoratedKey baseDecoratedKey; |
| private final ByteBuffer[] basePartitionKey; |
| |
| private final CFMetaData viewMetadata; |
| |
| private final Map<DecoratedKey, PartitionUpdate> updates = new HashMap<>(); |
| |
| // Reused internally to build a new entry |
| private final ByteBuffer[] currentViewEntryPartitionKey; |
| private final Row.Builder currentViewEntryBuilder; |
| |
| /** |
| * The type of type update action to perform to the view for a given base table |
| * update. |
| */ |
| private enum UpdateAction |
| { |
| NONE, // There was no view entry and none should be added |
| NEW_ENTRY, // There was no entry but there is one post-update |
| DELETE_OLD, // There was an entry but there is nothing after update |
| UPDATE_EXISTING, // There was an entry and the update modifies it |
| SWITCH_ENTRY // There was an entry and there is still one after update, |
| // but they are not the same one. |
| }; |
| |
| /** |
| * Creates a new {@code ViewUpdateBuilder}. |
| * |
| * @param view the view for which this will be building updates for. |
| * @param basePartitionKey the partition key for the base table partition for which |
| * we'll handle updates for. |
| * @param nowInSec the current time in seconds. Used to decide if data are live or not |
| * and as base reference for new deletions. |
| */ |
| public ViewUpdateGenerator(View view, DecoratedKey basePartitionKey, int nowInSec) |
| { |
| this.view = view; |
| this.nowInSec = nowInSec; |
| |
| this.baseMetadata = view.getDefinition().baseTableMetadata(); |
| this.baseDecoratedKey = basePartitionKey; |
| this.basePartitionKey = extractKeyComponents(basePartitionKey, baseMetadata.getKeyValidator()); |
| |
| this.viewMetadata = view.getDefinition().metadata; |
| |
| this.currentViewEntryPartitionKey = new ByteBuffer[viewMetadata.partitionKeyColumns().size()]; |
| this.currentViewEntryBuilder = BTreeRow.sortedBuilder(); |
| } |
| |
| private static ByteBuffer[] extractKeyComponents(DecoratedKey partitionKey, AbstractType<?> type) |
| { |
| return type instanceof CompositeType |
| ? ((CompositeType)type).split(partitionKey.getKey()) |
| : new ByteBuffer[]{ partitionKey.getKey() }; |
| } |
| |
| /** |
| * Adds to this generator the updates to be made to the view given a base table row |
| * before and after an update. |
| * |
| * @param existingBaseRow the base table row as it is before an update. |
| * @param mergedBaseRow the base table row after the update is applied (note that |
| * this is not just the new update, but rather the resulting row). |
| */ |
| public void addBaseTableUpdate(Row existingBaseRow, Row mergedBaseRow) |
| { |
| switch (updateAction(existingBaseRow, mergedBaseRow)) |
| { |
| case NONE: |
| return; |
| case NEW_ENTRY: |
| createEntry(mergedBaseRow); |
| return; |
| case DELETE_OLD: |
| deleteOldEntry(existingBaseRow); |
| return; |
| case UPDATE_EXISTING: |
| updateEntry(existingBaseRow, mergedBaseRow); |
| return; |
| case SWITCH_ENTRY: |
| createEntry(mergedBaseRow); |
| deleteOldEntry(existingBaseRow); |
| return; |
| } |
| } |
| |
| /** |
| * Returns the updates that needs to be done to the view given the base table updates |
| * passed to {@link #generateViewMutations}. |
| * |
| * @return the updates to do to the view. |
| */ |
| public Collection<PartitionUpdate> generateViewUpdates() |
| { |
| return updates.values(); |
| } |
| |
| /** |
| * Compute which type of action needs to be performed to the view for a base table row |
| * before and after an update. |
| */ |
| private UpdateAction updateAction(Row existingBaseRow, Row mergedBaseRow) |
| { |
| // Having existing empty is useful, it just means we'll insert a brand new entry for mergedBaseRow, |
| // but if we have no update at all, we shouldn't get there. |
| assert !mergedBaseRow.isEmpty(); |
| |
| // Note that none of the base PK columns will differ since we're intrinsically dealing |
| // with the same base row. So we have to check 3 things: |
| // 1) that the clustering doesn't have a null, which can happen for compact tables. If that's the case, |
| // there is no corresponding entries. |
| // 2) if there is a column not part of the base PK in the view PK, whether it is changed by the update. |
| // 3) whether mergedBaseRow actually match the view SELECT filter |
| |
| if (baseMetadata.isCompactTable()) |
| { |
| Clustering clustering = mergedBaseRow.clustering(); |
| for (int i = 0; i < clustering.size(); i++) |
| { |
| if (clustering.get(i) == null) |
| return UpdateAction.NONE; |
| } |
| } |
| |
| assert view.baseNonPKColumnsInViewPK.size() <= 1 : "We currently only support one base non-PK column in the view PK"; |
| if (view.baseNonPKColumnsInViewPK.isEmpty()) |
| { |
| // The view entry is necessarily the same pre and post update. |
| |
| // Note that we allow existingBaseRow to be null and treat it as empty (see MultiViewUpdateBuilder.generateViewsMutations). |
| boolean existingHasLiveData = existingBaseRow != null && existingBaseRow.hasLiveData(nowInSec); |
| boolean mergedHasLiveData = mergedBaseRow.hasLiveData(nowInSec); |
| return existingHasLiveData |
| ? (mergedHasLiveData ? UpdateAction.UPDATE_EXISTING : UpdateAction.DELETE_OLD) |
| : (mergedHasLiveData ? UpdateAction.NEW_ENTRY : UpdateAction.NONE); |
| } |
| |
| ColumnDefinition baseColumn = view.baseNonPKColumnsInViewPK.get(0); |
| assert !baseColumn.isComplex() : "A complex column couldn't be part of the view PK"; |
| Cell before = existingBaseRow == null ? null : existingBaseRow.getCell(baseColumn); |
| Cell after = mergedBaseRow.getCell(baseColumn); |
| |
| // If the update didn't modified this column, the cells will be the same object so it's worth checking |
| if (before == after) |
| return before == null ? UpdateAction.NONE : UpdateAction.UPDATE_EXISTING; |
| |
| if (!isLive(before)) |
| return isLive(after) ? UpdateAction.NEW_ENTRY : UpdateAction.NONE; |
| if (!isLive(after)) |
| return UpdateAction.DELETE_OLD; |
| |
| return baseColumn.cellValueType().compare(before.value(), after.value()) == 0 |
| ? UpdateAction.UPDATE_EXISTING |
| : UpdateAction.SWITCH_ENTRY; |
| } |
| |
| private boolean matchesViewFilter(Row baseRow) |
| { |
| return view.matchesViewFilter(baseDecoratedKey, baseRow, nowInSec); |
| } |
| |
| private boolean isLive(Cell cell) |
| { |
| return cell != null && cell.isLive(nowInSec); |
| } |
| |
| /** |
| * Creates a view entry corresponding to the provided base row. |
| * <p> |
| * This method checks that the base row does match the view filter before applying it. |
| */ |
| private void createEntry(Row baseRow) |
| { |
| // Before create a new entry, make sure it matches the view filter |
| if (!matchesViewFilter(baseRow)) |
| return; |
| |
| startNewUpdate(baseRow); |
| currentViewEntryBuilder.addPrimaryKeyLivenessInfo(computeLivenessInfoForEntry(baseRow)); |
| currentViewEntryBuilder.addRowDeletion(baseRow.deletion()); |
| |
| for (ColumnData data : baseRow) |
| { |
| ColumnDefinition viewColumn = view.getViewColumn(data.column()); |
| // If that base table column is not denormalized in the view, we had nothing to do. |
| // Alose, if it's part of the view PK it's already been taken into account in the clustering. |
| if (viewColumn == null || viewColumn.isPrimaryKeyColumn()) |
| continue; |
| |
| addColumnData(viewColumn, data); |
| } |
| |
| submitUpdate(); |
| } |
| |
| /** |
| * Creates the updates to apply to the existing view entry given the base table row before |
| * and after the update, assuming that the update hasn't changed to which view entry the |
| * row correspond (that is, we know the columns composing the view PK haven't changed). |
| * <p> |
| * This method checks that the base row (before and after) does match the view filter before |
| * applying anything. |
| */ |
| private void updateEntry(Row existingBaseRow, Row mergedBaseRow) |
| { |
| // While we know existingBaseRow and mergedBaseRow are corresponding to the same view entry, |
| // they may not match the view filter. |
| if (!matchesViewFilter(existingBaseRow)) |
| { |
| createEntry(mergedBaseRow); |
| return; |
| } |
| if (!matchesViewFilter(mergedBaseRow)) |
| { |
| deleteOldEntryInternal(existingBaseRow); |
| return; |
| } |
| |
| startNewUpdate(mergedBaseRow); |
| |
| // In theory, it may be the PK liveness and row deletion hasn't been change by the update |
| // and we could condition the 2 additions below. In practice though, it's as fast (if not |
| // faster) to compute those info than to check if they have changed so we keep it simple. |
| currentViewEntryBuilder.addPrimaryKeyLivenessInfo(computeLivenessInfoForEntry(mergedBaseRow)); |
| currentViewEntryBuilder.addRowDeletion(mergedBaseRow.deletion()); |
| |
| // We only add to the view update the cells from mergedBaseRow that differs from |
| // existingBaseRow. For that and for speed we can just cell pointer equality: if the update |
| // hasn't touched a cell, we know it will be the same object in existingBaseRow and |
| // mergedBaseRow (note that including more cells than we strictly should isn't a problem |
| // for correction, so even if the code change and pointer equality don't work anymore, it'll |
| // only a slightly inefficiency which we can fix then). |
| // Note: we could alternatively use Rows.diff() for this, but because it is a bit more generic |
| // than what we need here, it's also a bit less efficient (it allocates more in particular), |
| // and this might be called a lot of time for view updates. So, given that this is not a whole |
| // lot of code anyway, it's probably doing the diff manually. |
| PeekingIterator<ColumnData> existingIter = Iterators.peekingIterator(existingBaseRow.iterator()); |
| for (ColumnData mergedData : mergedBaseRow) |
| { |
| ColumnDefinition baseColumn = mergedData.column(); |
| ColumnDefinition viewColumn = view.getViewColumn(baseColumn); |
| // If that base table column is not denormalized in the view, we had nothing to do. |
| // Alose, if it's part of the view PK it's already been taken into account in the clustering. |
| if (viewColumn == null || viewColumn.isPrimaryKeyColumn()) |
| continue; |
| |
| ColumnData existingData = null; |
| // Find if there is data for that column in the existing row |
| while (existingIter.hasNext()) |
| { |
| int cmp = baseColumn.compareTo(existingIter.peek().column()); |
| if (cmp < 0) |
| break; |
| |
| ColumnData next = existingIter.next(); |
| if (cmp == 0) |
| { |
| existingData = next; |
| break; |
| } |
| } |
| |
| if (existingData == null) |
| { |
| addColumnData(viewColumn, mergedData); |
| continue; |
| } |
| |
| if (mergedData == existingData) |
| continue; |
| |
| if (baseColumn.isComplex()) |
| { |
| ComplexColumnData mergedComplexData = (ComplexColumnData)mergedData; |
| ComplexColumnData existingComplexData = (ComplexColumnData)existingData; |
| if (mergedComplexData.complexDeletion().supersedes(existingComplexData.complexDeletion())) |
| currentViewEntryBuilder.addComplexDeletion(viewColumn, mergedComplexData.complexDeletion()); |
| |
| PeekingIterator<Cell> existingCells = Iterators.peekingIterator(existingComplexData.iterator()); |
| for (Cell mergedCell : mergedComplexData) |
| { |
| Cell existingCell = null; |
| // Find if there is corresponding cell in the existing row |
| while (existingCells.hasNext()) |
| { |
| int cmp = baseColumn.cellPathComparator().compare(mergedCell.path(), existingCells.peek().path()); |
| if (cmp > 0) |
| break; |
| |
| Cell next = existingCells.next(); |
| if (cmp == 0) |
| { |
| existingCell = next; |
| break; |
| } |
| } |
| |
| if (mergedCell != existingCell) |
| addCell(viewColumn, mergedCell); |
| } |
| } |
| else |
| { |
| // Note that we've already eliminated the case where merged == existing |
| addCell(viewColumn, (Cell)mergedData); |
| } |
| } |
| |
| submitUpdate(); |
| } |
| |
| /** |
| * Deletes the view entry corresponding to the provided base row. |
| * <p> |
| * This method checks that the base row does match the view filter before bothering. |
| */ |
| private void deleteOldEntry(Row existingBaseRow) |
| { |
| // Before deleting an old entry, make sure it was matching the view filter (otherwise there is nothing to delete) |
| if (!matchesViewFilter(existingBaseRow)) |
| return; |
| |
| deleteOldEntryInternal(existingBaseRow); |
| } |
| |
| private void deleteOldEntryInternal(Row existingBaseRow) |
| { |
| startNewUpdate(existingBaseRow); |
| DeletionTime dt = new DeletionTime(computeTimestampForEntryDeletion(existingBaseRow), nowInSec); |
| currentViewEntryBuilder.addRowDeletion(Row.Deletion.shadowable(dt)); |
| submitUpdate(); |
| } |
| |
| /** |
| * Computes the partition key and clustering for a new view entry, and setup the internal |
| * row builder for the new row. |
| * |
| * This assumes that there is corresponding entry, i.e. no values for the partition key and |
| * clustering are null (since we have eliminated that case through updateAction). |
| */ |
| private void startNewUpdate(Row baseRow) |
| { |
| ByteBuffer[] clusteringValues = new ByteBuffer[viewMetadata.clusteringColumns().size()]; |
| for (ColumnDefinition viewColumn : viewMetadata.primaryKeyColumns()) |
| { |
| ColumnDefinition baseColumn = view.getBaseColumn(viewColumn); |
| ByteBuffer value = getValueForPK(baseColumn, baseRow); |
| if (viewColumn.isPartitionKey()) |
| currentViewEntryPartitionKey[viewColumn.position()] = value; |
| else |
| clusteringValues[viewColumn.position()] = value; |
| } |
| |
| currentViewEntryBuilder.newRow(new Clustering(clusteringValues)); |
| } |
| |
| private LivenessInfo computeLivenessInfoForEntry(Row baseRow) |
| { |
| /* |
| * We need to compute both the timestamp and expiration. |
| * |
| * For the timestamp, it makes sense to use the bigger timestamp for all view PK columns. |
| * |
| * This is more complex for the expiration. We want to maintain consistency between the base and the view, so the |
| * entry should only exist as long as the base row exists _and_ has non-null values for all the columns that are part |
| * of the view PK. |
| * Which means we really have 2 cases: |
| * 1) either the columns for the base and view PKs are exactly the same: in that case, the view entry should live |
| * as long as the base row lives. This means the view entry should only expire once *everything* in the base row |
| * has expired. Which means the row TTL should be the max of any other TTL. |
| * 2) or there is a column that is not in the base PK but is in the view PK (we can only have one so far, we'll need |
| * to slightly adapt if we allow more later): in that case, as long as that column lives the entry does too, but |
| * as soon as it expires (or is deleted for that matter) the entry also should expire. So the expiration for the |
| * view is the one of that column, irregarding of any other expiration. |
| * To take an example of that case, if you have: |
| * CREATE TABLE t (a int, b int, c int, PRIMARY KEY (a, b)) |
| * CREATE MATERIALIZED VIEW mv AS SELECT * FROM t WHERE c IS NOT NULL AND a IS NOT NULL AND b IS NOT NULL PRIMARY KEY (c, a, b) |
| * INSERT INTO t(a, b) VALUES (0, 0) USING TTL 3; |
| * UPDATE t SET c = 0 WHERE a = 0 AND b = 0; |
| * then even after 3 seconds elapsed, the row will still exist (it just won't have a "row marker" anymore) and so |
| * the MV should still have a corresponding entry. |
| */ |
| assert view.baseNonPKColumnsInViewPK.size() <= 1; // This may change, but is currently an enforced limitation |
| |
| LivenessInfo baseLiveness = baseRow.primaryKeyLivenessInfo(); |
| |
| if (view.baseNonPKColumnsInViewPK.isEmpty()) |
| { |
| int ttl = baseLiveness.ttl(); |
| int expirationTime = baseLiveness.localExpirationTime(); |
| for (Cell cell : baseRow.cells()) |
| { |
| if (cell.ttl() > ttl) |
| { |
| ttl = cell.ttl(); |
| expirationTime = cell.localDeletionTime(); |
| } |
| } |
| return ttl == baseLiveness.ttl() |
| ? baseLiveness |
| : LivenessInfo.create(baseLiveness.timestamp(), ttl, expirationTime); |
| } |
| |
| ColumnDefinition baseColumn = view.baseNonPKColumnsInViewPK.get(0); |
| Cell cell = baseRow.getCell(baseColumn); |
| assert isLive(cell) : "We shouldn't have got there is the base row had no associated entry"; |
| |
| long timestamp = Math.max(baseLiveness.timestamp(), cell.timestamp()); |
| return LivenessInfo.create(timestamp, cell.ttl(), cell.localDeletionTime()); |
| } |
| |
| private long computeTimestampForEntryDeletion(Row baseRow) |
| { |
| // We delete the old row with it's row entry timestamp using a shadowable deletion. |
| // We must make sure that the deletion deletes everything in the entry (or the entry will |
| // still show up), so we must use the bigger timestamp found in the existing row (for any |
| // column included in the view at least). |
| // TODO: We have a problem though: if the entry is "resurected" by a later update, we would |
| // need to ensure that the timestamp for then entry then is bigger than the tombstone |
| // we're just inserting, which is not currently guaranteed. |
| // This is a bug for a separate ticket though. |
| long timestamp = baseRow.primaryKeyLivenessInfo().timestamp(); |
| for (ColumnData data : baseRow) |
| { |
| if (!view.getDefinition().includes(data.column().name)) |
| continue; |
| |
| timestamp = Math.max(timestamp, data.maxTimestamp()); |
| } |
| return timestamp; |
| } |
| |
| private void addColumnData(ColumnDefinition viewColumn, ColumnData baseTableData) |
| { |
| assert viewColumn.isComplex() == baseTableData.column().isComplex(); |
| if (!viewColumn.isComplex()) |
| { |
| addCell(viewColumn, (Cell)baseTableData); |
| return; |
| } |
| |
| ComplexColumnData complexData = (ComplexColumnData)baseTableData; |
| currentViewEntryBuilder.addComplexDeletion(viewColumn, complexData.complexDeletion()); |
| for (Cell cell : complexData) |
| addCell(viewColumn, cell); |
| } |
| |
| private void addCell(ColumnDefinition viewColumn, Cell baseTableCell) |
| { |
| assert !viewColumn.isPrimaryKeyColumn(); |
| currentViewEntryBuilder.addCell(baseTableCell.withUpdatedColumn(viewColumn)); |
| } |
| |
| /** |
| * Finish building the currently updated view entry and add it to the other built |
| * updates. |
| */ |
| private void submitUpdate() |
| { |
| Row row = currentViewEntryBuilder.build(); |
| // I'm not sure we can reach there is there is nothing is updated, but adding an empty row breaks things |
| // and it costs us nothing to be prudent here. |
| if (row.isEmpty()) |
| return; |
| |
| DecoratedKey partitionKey = makeCurrentPartitionKey(); |
| PartitionUpdate update = updates.get(partitionKey); |
| if (update == null) |
| { |
| // We can't really know which columns of the view will be updated nor how many row will be updated for this key |
| // so we rely on hopefully sane defaults. |
| update = new PartitionUpdate(viewMetadata, partitionKey, viewMetadata.partitionColumns(), 4); |
| updates.put(partitionKey, update); |
| } |
| update.add(row); |
| } |
| |
| private DecoratedKey makeCurrentPartitionKey() |
| { |
| ByteBuffer rawKey = viewMetadata.partitionKeyColumns().size() == 1 |
| ? currentViewEntryPartitionKey[0] |
| : CompositeType.build(currentViewEntryPartitionKey); |
| |
| return viewMetadata.decorateKey(rawKey); |
| } |
| |
| private ByteBuffer getValueForPK(ColumnDefinition column, Row row) |
| { |
| switch (column.kind) |
| { |
| case PARTITION_KEY: |
| return basePartitionKey[column.position()]; |
| case CLUSTERING: |
| return row.clustering().get(column.position()); |
| default: |
| // This shouldn't NPE as we shouldn't get there if the value can be null (or there is a bug in updateAction()) |
| return row.getCell(column).value(); |
| } |
| } |
| } |