Skip to content

Avoid caching full query result for queries with generic sort and LIM… #121

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Avoid caching full query result for queries with generic sort and LIM… #121

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
29d7965
Avoid caching full query result for queries with generic sort and LIM…
markoszah Jun 4, 2024
c8bb12b
added comment
markoszah Jun 5, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 5 additions & 5 deletions driver/src/main/java/oracle/nosql/driver/http/Client.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -630,7 +630,7 @@ public Result execute(Request kvRequest) {
*/
kvRequest.setTimeoutInternal(thisIterationTimeoutMs);
serialVersionUsed = writeContent(buffer, kvRequest,
queryVersionUsed);
queryVersionUsed);
kvRequest.setTimeoutInternal(timeoutMs);

/*
Expand Down Expand Up @@ -1616,11 +1616,11 @@ private synchronized boolean decrementQueryVersion(short versionUsed) {
if (queryVersion != versionUsed) {
return true;
}
if (queryVersion == QueryDriver.QUERY_V4) {
queryVersion = QueryDriver.QUERY_V3;
return true;
if (queryVersion == QueryDriver.QUERY_V3) {
return false;
}
return false;
--queryVersion;
return true;
}

/**
Expand Down
6 changes: 3 additions & 3 deletions driver/src/main/java/oracle/nosql/driver/ops/serde/nson/NsonSerializerFactory.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1008,7 +1008,7 @@ private static void deserializePrepareOrQuery(

} else if (name.equals(DRIVER_QUERY_PLAN)) {
dpi = getDriverPlanInfo(Nson.readNsonBinary(in),
serialVersion);
queryVersion);

} else if (name.equals(REACHED_LIMIT) && qres != null) {
qres.setReachedLimit(Nson.readNsonBoolean(in));
Expand Down Expand Up @@ -1179,15 +1179,15 @@ private static void readPhase1Results(byte[] arr, QueryResult result)
}

private static DriverPlanInfo getDriverPlanInfo(byte[] arr,
short serialVersion)
short queryVersion)
throws IOException {
if (arr == null || arr.length == 0) {
return null;
}
ByteBuf buf = Unpooled.wrappedBuffer(arr);
ByteInputStream bis = new NettyByteInputStream(buf);
DriverPlanInfo dpi = new DriverPlanInfo();
dpi.driverQueryPlan = PlanIter.deserializeIter(bis, serialVersion);
dpi.driverQueryPlan = PlanIter.deserializeIter(bis, queryVersion);
if (dpi.driverQueryPlan == null) {
return null;
}
Expand Down
3 changes: 3 additions & 0 deletions driver/src/main/java/oracle/nosql/driver/query/PlanIter.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -306,6 +306,9 @@ protected abstract void displayContent(
StringBuilder sb,
QueryFormatter formatter);

/*
* Note: the serialVersion param is actually the queryVersion.
*/
public static PlanIter deserializeIter(
ByteInputStream in,
short serialVersion) throws IOException {
Expand Down
5 changes: 4 additions & 1 deletion driver/src/main/java/oracle/nosql/driver/query/QueryDriver.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,10 @@ public class QueryDriver {
/* added query name in QueryRequest */
public static short QUERY_V4 = 4;

public static short QUERY_VERSION = QUERY_V4;
/* added limit iter field in SortIter */
public static short QUERY_V5 = 5;

public static short QUERY_VERSION = QUERY_V5;

private static final int BATCH_SIZE = 100;

Expand Down
217 changes: 193 additions & 24 deletions driver/src/main/java/oracle/nosql/driver/query/SortIter.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.PriorityQueue;

import oracle.nosql.driver.query.PlanIterState.StateEnum;
import oracle.nosql.driver.util.ByteInputStream;
Expand All @@ -25,35 +26,120 @@
*/
public class SortIter extends PlanIter {

private class CompareFunction implements Comparator<MapValue> {

RuntimeControlBlock theRCB;

CompareFunction(RuntimeControlBlock rcb) {
theRCB = rcb;
}

@Override
public int compare(MapValue v1, MapValue v2) {

return Compare.sortResults(theRCB,
v1,
v2,
theSortFields,
theSortSpecs);
}
}

private static class ReverseCompareFunction implements Comparator<MapValue> {

CompareFunction theComparator;

ReverseCompareFunction(CompareFunction comparator) {
theComparator = comparator;
}

@Override
public int compare(MapValue v1, MapValue v2) {
return -theComparator.compare(v1, v2);
}
}

private static class SortIterState extends PlanIterState {

final ArrayList<MapValue> theResults;
CompareFunction theComparator;

/*
* If theLimit is < 0, the SortIter will cache the full query result
* set (in theResults) and then sort it and return it one result at a
* time. theLimit will be > 0 if the query contains LIMIT clause. In
* this case, theLimit is the sum of the OFFSET and LIMIT values
* specified in the query and the SortIter does not need to cache more
* than theLimit results. Specifically, if theLimit is > 0, the SortIter
* works as follows:
* a. Up to theLimit results are initially cached in theResults.
* b. If there are no more than theLimit results, theResults is sorted
* and then theSortIter returns these sorted result one at a time.
* c. Otherwise, when theLimit results have been cached, they are
* transfered from theResults to theResultsQueue, which keeps
* the results sorted. Any subsequent result R is compared with
* greatest result, R_MAX, in the queue: if it R > R_MAX, it is
* discarded; otherwise, R is inserted in the queue and R_MAX is
* removed from the queue and discarded.
* d. Note that PriorityQueue gives access to the least result in
* the queue, not the greatest. To handle this, we use the
* ReverseCompareFunction with theResultsQueue, to sort the
* results in the reverse of the desired order. Then, when the
* full result set has been computed, the SortIter transfers
* the results in theResultsQueue to theResultsArray in the
* correct order. After this point, the SortIter returns the
* the results in theResultsArray, one at a time.
*/
int theLimit = -1;

ArrayList<MapValue> theResults;
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Please add some comments here that explain why there are three collections (list, queue, array) and when/how each are used.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Done.


PriorityQueue<MapValue> theResultsQueue;

MapValue[] theResultsArray;

int theNumResults;

int theCurrResult;

public SortIterState() {
public SortIterState(RuntimeControlBlock rcb, SortIter iter, int limit) {
super();
theResults = new ArrayList<MapValue>(128);
theLimit = limit;
if (theLimit > 0) {
theResults = new ArrayList<MapValue>(theLimit);
} else {
theResults = new ArrayList<MapValue>(4096);
}
theComparator = iter.new CompareFunction(rcb);
}

@Override
public void done() {
super.done();
theCurrResult = 0;
theResults.clear();
theResults = null;
theResultsQueue = null;
theResultsArray = null;
}

@Override
public void reset(PlanIter iter) {
super.reset(iter);
theCurrResult = 0;
theResults.clear();
theNumResults = 0;
if (theLimit > 0) {
theResults = new ArrayList<MapValue>(theLimit);
} else {
theResults = new ArrayList<MapValue>(4096);
}
theResultsQueue = null;
theResultsArray = null;
}

@Override
public void close() {
super.close();
theResults.clear();
theResults = null;
theResultsQueue = null;
theResultsArray = null;
}
}

Expand All @@ -63,13 +149,15 @@ public void close() {

private final SortSpec[] theSortSpecs;

private final PlanIter theLimit;

private final boolean theCountMemory;

public SortIter(ByteInputStream in, PlanIterKind kind, short serialVersion)
public SortIter(ByteInputStream in, PlanIterKind kind, short queryVersion)
throws IOException {

super(in, serialVersion);
theInput = deserializeIter(in, serialVersion);
super(in, queryVersion);
theInput = deserializeIter(in, queryVersion);

theSortFields = SerializationUtil.readStringArray(in);
theSortSpecs = readSortSpecs(in);
Expand All @@ -79,6 +167,12 @@ public SortIter(ByteInputStream in, PlanIterKind kind, short serialVersion)
} else {
theCountMemory = true;
}

if (queryVersion >= QueryDriver.QUERY_V5) {
theLimit = deserializeIter(in, queryVersion);
} else {
theLimit = null;
}
}

@Override
Expand All @@ -93,7 +187,17 @@ PlanIter getInputIter() {

@Override
public void open(RuntimeControlBlock rcb) {
SortIterState state = new SortIterState();

int limit = - 1;

if (theLimit != null) {
theLimit.open(rcb);
theLimit.next(rcb);
FieldValue val = rcb.getRegVal(theLimit.getResultReg());
limit = val.getInt();
}

SortIterState state = new SortIterState(rcb, this, limit);
rcb.setState(theStatePos, state);
theInput.open(rcb);
}
Expand Down Expand Up @@ -143,11 +247,55 @@ public boolean next(RuntimeControlBlock rcb) {
}
}

state.theResults.add(v);
if (state.theLimit < 0) {
state.theResults.add(v);

if (theCountMemory) {
long sz = v.sizeof() + SizeOf.OBJECT_REF_OVERHEAD;
rcb.incMemoryConsumption(sz);
}
} else if (state.theResults != null &&
state.theResults.size() < state.theLimit) {

state.theResults.add(v);

if (theCountMemory) {
long sz = v.sizeof() + SizeOf.OBJECT_REF_OVERHEAD;
rcb.incMemoryConsumption(sz);
}

if (state.theResults.size() == state.theLimit) {

ReverseCompareFunction comparator =
new ReverseCompareFunction(state.theComparator);

state.theResultsQueue = new PriorityQueue<>(comparator);

if (theCountMemory) {
long sz = v.sizeof() + SizeOf.OBJECT_REF_OVERHEAD;
rcb.incMemoryConsumption(sz);
for (MapValue result : state.theResults) {
state.theResultsQueue.add(result);
}
state.theResults = null;
}
} else {
MapValue lastResult = state.theResultsQueue.peek();

if (state.theComparator.compare(lastResult, v) > 0) {

state.theResultsQueue.remove();
state.theResultsQueue.add(v);

if (rcb.getTraceLevel() >= 4) {
rcb.trace("SortIter: added top result: " + v +
"\nin place of " + lastResult);
}

if (theCountMemory) {
long sz = v.sizeof();
rcb.incMemoryConsumption(sz);
sz = lastResult.sizeof();
rcb.decMemoryConsumption(sz);
}
}
}

more = theInput.next(rcb);
Expand All @@ -157,22 +305,43 @@ public boolean next(RuntimeControlBlock rcb) {
return false;
}

state.theResults.sort(
(v1, v2) -> Compare.sortResults(rcb,
v1,
v2,
theSortFields,
theSortSpecs));
if (state.theResultsQueue != null) {
/* Move the results from the queue to an array, maintaining their
* sort order. This is needed because iterating over the queue
* using an Iterator does not guarantee that the results will be
* retrieved in their sorted order. */
state.theResultsArray = new MapValue[state.theLimit];

int i = state.theLimit - 1;
while (!state.theResultsQueue.isEmpty()) {
MapValue result = state.theResultsQueue.remove();
state.theResultsArray[i] = result;
--i;
}

state.theResultsQueue = null;
state.theNumResults = state.theLimit;
} else {
state.theResults.sort(state.theComparator);
state.theNumResults = state.theResults.size();
}

state.setState(StateEnum.RUNNING);
}

if (state.theCurrResult < state.theResults.size()) {
if (state.theCurrResult < state.theNumResults) {

MapValue v;
if (state.theResultsArray == null) {
v = state.theResults.get(state.theCurrResult);
state.theResults.set(state.theCurrResult, null);
} else {
v = state.theResultsArray[state.theCurrResult];
state.theResultsArray[state.theCurrResult] = null;
}

MapValue v = state.theResults.get(state.theCurrResult);
v.convertEmptyToNull();
rcb.setRegVal(theResultReg, v);
state.theResults.set(state.theCurrResult, null);
++state.theCurrResult;
return true;
}
Expand Down