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Prepared statement performance fixes #11

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merged 1 commit into from
Jul 1, 2018
Merged

Prepared statement performance fixes #11

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6 changes: 3 additions & 3 deletions src/main/java/com/microsoft/sqlserver/jdbc/ParsedSQLMetadata.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,13 +14,13 @@
final class ParsedSQLCacheItem {
/** The SQL text AFTER processing. */
String processedSQL;
int parameterCount;
int[] parameterPositions;
String procedureName;
boolean bReturnValueSyntax;

ParsedSQLCacheItem(String processedSQL, int parameterCount, String procedureName, boolean bReturnValueSyntax) {
ParsedSQLCacheItem(String processedSQL, int[] parameterPositions, String procedureName, boolean bReturnValueSyntax) {
this.processedSQL = processedSQL;
this.parameterCount = parameterCount;
this.parameterPositions = parameterPositions;
this.procedureName = procedureName;
this.bReturnValueSyntax = bReturnValueSyntax;
}
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52 changes: 34 additions & 18 deletions src/main/java/com/microsoft/sqlserver/jdbc/SQLServerConnection.java
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Expand Up @@ -36,6 +36,7 @@
import java.sql.Statement;
import java.sql.Struct;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.HashMap;
Expand Down Expand Up @@ -123,11 +124,13 @@ static class CityHash128Key {

CityHash128Key(String sql,
String parametersDefinition) {
this(String.format("%s%s", sql, parametersDefinition));
this(sql + parametersDefinition);
}

CityHash128Key(String s) {
segments = CityHash.cityHash128(s.getBytes(), 0, s.length());
byte[] bytes = new byte[s.length()];
s.getBytes(0, s.length(), bytes, 0);
segments = CityHash.cityHash128(bytes, 0, bytes.length);
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@brettwooldridge brettwooldridge Jun 27, 2018 •
edited
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@RDearnaley I would suggest going ahead with the slightly safer:

byte[] bytes = new byte[s.length() * 2];
for (int i = 0; i < s.length(); i++) {
   final int c = s.charAt(i);
   bytes[i * 2] = (byte) c;
   bytes[(i * 2) + 1] = (byte)(c >> 8);
}
segments = CityHash.cityHash128(bytes, 0, bytes.length);

1 Receiving the charAt() into an int avoids one implicit conversion, as shift operators are not supported on char directly and the (byte) c cast also likely inflates to an int before casting.

}

public boolean equals(Object obj) {
Expand Down Expand Up @@ -260,9 +263,9 @@ static ParsedSQLCacheItem parseAndCacheSQL(CityHash128Key key, String sql) thro
String parsedSql = translator.translate(sql);
String procName = translator.getProcedureName(); // may return null
boolean returnValueSyntax = translator.hasReturnValueSyntax();
int paramCount = countParams(parsedSql);
int[] parameterPositions = locateParams(parsedSql);

ParsedSQLCacheItem cacheItem = new ParsedSQLCacheItem (parsedSql, paramCount, procName, returnValueSyntax);
ParsedSQLCacheItem cacheItem = new ParsedSQLCacheItem (parsedSql, parameterPositions, procName, returnValueSyntax);
parsedSQLCache.putIfAbsent(key, cacheItem);
return cacheItem;
}
Expand All @@ -283,22 +286,28 @@ static ParsedSQLCacheItem parseAndCacheSQL(CityHash128Key key, String sql) thro
private boolean disableStatementPooling = true;

/**
* Find statement parameters.
* Locate statement parameters.
*
* @param sql
* SQL text to parse for number of parameters to intialize.
* SQL text to parse for positions of parameters to intialize.
*/
private static int countParams(String sql) {
int nParams = 0;

// Figure out the expected number of parameters by counting the
// parameter placeholders in the SQL string.
int offset = -1;
while ((offset = ParameterUtils.scanSQLForChar('?', sql, ++offset)) < sql.length())
++nParams;

return nParams;
}
private static int[] locateParams(String sql) {
List<Integer> parameterPositions = new ArrayList<Integer>(0);

// Locate the parameter placeholders in the SQL string.
int offset = -1;
while ((offset = ParameterUtils.scanSQLForChar('?', sql, ++offset)) < sql.length()) {
parameterPositions.add(offset);
}

// Convert to int[]
int[] result = new int[parameterPositions.size()];
int i = 0;
for (Integer parameterPosition : parameterPositions) {
result[i++] = parameterPosition;
}
return result;
}

SqlFedAuthToken getAuthenticationResult() {
return fedAuthToken;
Expand Down Expand Up @@ -5309,6 +5318,7 @@ public void endRequest() throws SQLFeatureNotSupportedException {
static final char[] OUT = {' ', 'O', 'U', 'T'};

/* L0 */ String replaceParameterMarkers(String sqlSrc,
int[] paramPositions,
Parameter[] params,
boolean isReturnValueSyntax) throws SQLServerException {
final int MAX_PARAM_NAME_LEN = 6;
Expand All @@ -5319,7 +5329,13 @@ public void endRequest() throws SQLFeatureNotSupportedException {

int paramIndex = 0;
while (true) {
int srcEnd = ParameterUtils.scanSQLForChar('?', sqlSrc, srcBegin);
int srcEnd;
if (paramIndex >= paramPositions.length) {
srcEnd = sqlSrc.length();
}
else {
srcEnd = paramPositions[paramIndex];
}
sqlSrc.getChars(srcBegin, srcEnd, sqlDst, dstBegin);
dstBegin += srcEnd - srcBegin;

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1 change: 1 addition & 0 deletions src/main/java/com/microsoft/sqlserver/jdbc/SQLServerParameterMetaData.java
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Expand Up @@ -608,6 +608,7 @@ private void checkClosed() throws SQLServerException {
if (con.getServerMajorVersion() >= SQL_SERVER_2012_VERSION) {
// new implementation for SQL verser 2012 and above
String preparedSQL = con.replaceParameterMarkers(((SQLServerPreparedStatement) stmtParent).userSQL,
((SQLServerPreparedStatement) stmtParent).userSQLParamPositions,
((SQLServerPreparedStatement) stmtParent).inOutParam, ((SQLServerPreparedStatement) stmtParent).bReturnValueSyntax);

SQLServerCallableStatement cstmt = (SQLServerCallableStatement) con.prepareCall("exec sp_describe_undeclared_parameters ?");
Expand Down
8 changes: 6 additions & 2 deletions src/main/java/com/microsoft/sqlserver/jdbc/SQLServerPreparedStatement.java
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Expand Up @@ -64,6 +64,9 @@ public class SQLServerPreparedStatement extends SQLServerStatement implements IS
/** Processed SQL statement text, may not be same as what user initially passed. */
final String userSQL;

/** Parameter positions in processed SQL statement text. */
final int[] userSQLParamPositions;

/** SQL statement with expanded parameter tokens */
private String preparedSQL;

Expand Down Expand Up @@ -204,7 +207,8 @@ String getClassNameInternal() {
procedureName = parsedSQL.procedureName;
bReturnValueSyntax = parsedSQL.bReturnValueSyntax;
userSQL = parsedSQL.processedSQL;
initParams(parsedSQL.parameterCount);
userSQLParamPositions = parsedSQL.parameterPositions;
initParams(userSQLParamPositions.length);
}

/**
Expand Down Expand Up @@ -342,7 +346,7 @@ private boolean buildPreparedStrings(Parameter[] params,
preparedTypeDefinitions = newTypeDefinitions;

/* Replace the parameter marker '?' with the param numbers @p1, @p2 etc */
preparedSQL = connection.replaceParameterMarkers(userSQL, params, bReturnValueSyntax);
preparedSQL = connection.replaceParameterMarkers(userSQL, userSQLParamPositions, params, bReturnValueSyntax);
if (bRequestedGeneratedKeys)
preparedSQL = preparedSQL + identityQuery;

Expand Down