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/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.command;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import org.h2.api.DatabaseEventListener;
import org.h2.api.ErrorCode;
import org.h2.engine.Database;
import org.h2.engine.DbObject;
import org.h2.engine.SessionLocal;
import org.h2.expression.Expression;
import org.h2.expression.Parameter;
import org.h2.message.DbException;
import org.h2.message.Trace;
import org.h2.result.ResultInterface;
import org.h2.table.TableView;
import org.h2.util.HasSQL;
/**
* A prepared statement.
*/
public abstract class Prepared {
/**
* The session.
*/
protected SessionLocal session;
/**
* The SQL string.
*/
protected String sqlStatement;
/**
* The SQL tokens.
*/
protected ArrayList sqlTokens;
/**
* Whether to create a new object (for indexes).
*/
protected boolean create = true;
/**
* The list of parameters.
*/
protected ArrayList parameters;
private boolean withParamValues;
/**
* If the query should be prepared before each execution. This is set for
* queries with LIKE ?, because the query plan depends on the parameter
* value.
*/
protected boolean prepareAlways;
private long modificationMetaId;
private Command command;
/**
* Used to preserve object identities on database startup. {@code 0} if
* object is not stored, {@code -1} if object is stored and its ID is
* already read, {@code >0} if object is stored and its id is not yet read.
*/
private int persistedObjectId;
private long currentRowNumber;
private int rowScanCount;
/**
* Common table expressions (CTE) in queries require us to create temporary views,
* which need to be cleaned up once a command is done executing.
*/
private List cteCleanups;
/**
* Create a new object.
*
* @param session the session
*/
public Prepared(SessionLocal session) {
this.session = session;
modificationMetaId = getDatabase().getModificationMetaId();
}
/**
* Check if this command is transactional.
* If it is not, then it forces the current transaction to commit.
*
* @return true if it is
*/
public abstract boolean isTransactional();
/**
* Get an empty result set containing the meta data.
*
* @return the result set
*/
public abstract ResultInterface queryMeta();
/**
* Get the command type as defined in CommandInterface
*
* @return the statement type
*/
public abstract int getType();
/**
* Check if this command is read only.
*
* @return true if it is
*/
public boolean isReadOnly() {
return false;
}
/**
* Check if the statement needs to be re-compiled.
*
* @return true if it must
*/
public boolean needRecompile() {
Database db = getDatabase();
if (db == null) {
throw DbException.get(ErrorCode.CONNECTION_BROKEN_1, "database closed");
}
// parser: currently, compiling every create/drop/... twice
// because needRecompile return true even for the first execution
return prepareAlways ||
modificationMetaId < db.getModificationMetaId() ||
db.getSettings().recompileAlways;
}
/**
* Get the meta data modification id of the database when this statement was
* compiled.
*
* @return the meta data modification id
*/
long getModificationMetaId() {
return modificationMetaId;
}
/**
* Set the meta data modification id of this statement.
*
* @param id the new id
*/
void setModificationMetaId(long id) {
this.modificationMetaId = id;
}
/**
* Set the parameter list of this statement.
*
* @param parameters the parameter list
*/
public void setParameterList(ArrayList parameters) {
this.parameters = parameters;
}
/**
* Get the parameter list.
*
* @return the parameter list
*/
public ArrayList getParameters() {
return parameters;
}
/**
* Returns whether values of parameters were specified in SQL.
*
* @return are values of parameters were specified in SQL
*/
public boolean isWithParamValues() {
return withParamValues;
}
/**
* Sets whether values of parameters were specified in SQL.
*
* @param withParamValues
* are values of parameters were specified in SQL
*/
public void setWithParamValues(boolean withParamValues) {
this.withParamValues = withParamValues;
}
/**
* Check if all parameters have been set.
*
* @throws DbException if any parameter has not been set
*/
protected void checkParameters() {
if (persistedObjectId < 0) {
// restore original persistedObjectId on Command re-run
// i.e. due to concurrent update
persistedObjectId = ~persistedObjectId;
}
if (parameters != null) {
for (Parameter param : parameters) {
param.checkSet();
}
}
}
/**
* Set the command.
*
* @param command the new command
*/
public void setCommand(Command command) {
this.command = command;
}
/**
* Check if this object is a query.
*
* @return true if it is
*/
public boolean isQuery() {
return false;
}
/**
* Prepare this statement.
*/
public void prepare() {
// nothing to do
}
/**
* Execute the statement.
*
* @return the update count
* @throws DbException if it is a query
*/
public long update() {
throw DbException.get(ErrorCode.METHOD_NOT_ALLOWED_FOR_QUERY);
}
/**
* Execute the query.
*
* @param maxrows the maximum number of rows to return
* @return the result set
* @throws DbException if it is not a query
*/
@SuppressWarnings("unused")
public ResultInterface query(long maxrows) {
throw DbException.get(ErrorCode.METHOD_ONLY_ALLOWED_FOR_QUERY);
}
/**
* Set the SQL statement.
*
* @param sql the SQL statement
* @param sqlTokens the SQL tokens
*/
public final void setSQL(String sql, ArrayList sqlTokens) {
this.sqlStatement = sql;
this.sqlTokens = sqlTokens;
}
/**
* Get the SQL statement.
*
* @return the SQL statement
*/
public final String getSQL() {
return sqlStatement;
}
/**
* Get the SQL tokens.
*
* @return the SQL tokens
*/
public final ArrayList getSQLTokens() {
return sqlTokens;
}
/**
* Get the object id to use for the database object that is created in this
* statement. This id is only set when the object is already persisted.
* If not set, this method returns 0.
*
* @return the object id or 0 if not set
*/
public int getPersistedObjectId() {
int id = persistedObjectId;
return id >= 0 ? id : 0;
}
/**
* Get the current object id, or get a new id from the database. The object
* id is used when creating new database object (CREATE statement). This
* method may be called only once.
*
* @return the object id
*/
protected int getObjectId() {
int id = persistedObjectId;
if (id == 0) {
id = getDatabase().allocateObjectId();
} else if (id < 0) {
throw DbException.getInternalError("Prepared.getObjectId() was called before");
}
persistedObjectId = ~persistedObjectId; // while negative, it can be restored later
return id;
}
/**
* Get the SQL statement with the execution plan.
*
* @param sqlFlags formatting flags
* @return the execution plan
*/
public String getPlanSQL(int sqlFlags) {
return null;
}
/**
* Check if this statement was canceled.
*
* @throws DbException if it was canceled
*/
public void checkCanceled() {
session.checkCanceled();
Command c = command != null ? command : session.getCurrentCommand();
if (c != null) {
c.checkCanceled();
}
}
/**
* Set the persisted object id for this statement.
*
* @param i the object id
*/
public void setPersistedObjectId(int i) {
this.persistedObjectId = i;
this.create = false;
}
/**
* Set the session for this statement.
*
* @param currentSession the new session
*/
public void setSession(SessionLocal currentSession) {
this.session = currentSession;
}
/**
* Print information about the statement executed if info trace level is
* enabled.
* @param database to update statistics
* @param startTimeNanos when the statement was started
* @param rowCount the query or update row count
*/
void trace(Database database, long startTimeNanos, long rowCount) {
if (session.getTrace().isInfoEnabled() && startTimeNanos > 0) {
long deltaTimeNanos = System.nanoTime() - startTimeNanos;
String params = Trace.formatParams(parameters);
session.getTrace().infoSQL(sqlStatement, params, rowCount, deltaTimeNanos / 1_000_000L);
}
// startTime_nanos can be zero for the command that actually turns on
// statistics
if (database != null && database.getQueryStatistics() && startTimeNanos != 0) {
long deltaTimeNanos = System.nanoTime() - startTimeNanos;
database.getQueryStatisticsData().update(toString(), deltaTimeNanos, rowCount);
}
}
/**
* Set the prepare always flag.
* If set, the statement is re-compiled whenever it is executed.
*
* @param prepareAlways the new value
*/
public void setPrepareAlways(boolean prepareAlways) {
this.prepareAlways = prepareAlways;
}
/**
* Set the current row number.
*
* @param rowNumber the row number
*/
public void setCurrentRowNumber(long rowNumber) {
if ((++rowScanCount & 127) == 0) {
checkCanceled();
}
this.currentRowNumber = rowNumber;
setProgress();
}
/**
* Get the current row number.
*
* @return the row number
*/
public long getCurrentRowNumber() {
return currentRowNumber;
}
/**
* Notifies query progress via the DatabaseEventListener
*/
private void setProgress() {
if ((currentRowNumber & 127) == 0) {
getDatabase().setProgress(DatabaseEventListener.STATE_STATEMENT_PROGRESS, sqlStatement,
currentRowNumber, 0L);
}
}
/**
* Convert the statement to a String.
*
* @return the SQL statement
*/
@Override
public String toString() {
return sqlStatement;
}
/**
* Get the SQL snippet of the expression list.
*
* @param list the expression list
* @return the SQL snippet
*/
public static String getSimpleSQL(Expression[] list) {
return Expression.writeExpressions(new StringBuilder(), list, HasSQL.TRACE_SQL_FLAGS).toString();
}
/**
* Set the SQL statement of the exception to the given row.
*
* @param e the exception
* @param rowId the row number
* @param values the values of the row
* @return the exception
*/
protected final DbException setRow(DbException e, long rowId, String values) {
StringBuilder buff = new StringBuilder();
if (sqlStatement != null) {
buff.append(sqlStatement);
}
buff.append(" -- ");
if (rowId > 0) {
buff.append("row #").append(rowId + 1).append(' ');
}
buff.append('(').append(values).append(')');
return e.addSQL(buff.toString());
}
public boolean isCacheable() {
return false;
}
/**
* @return the temporary views created for CTE's.
*/
public List getCteCleanups() {
return cteCleanups;
}
/**
* Set the temporary views created for CTE's.
*
* @param cteCleanups the temporary views
*/
public void setCteCleanups(List cteCleanups) {
this.cteCleanups = cteCleanups;
}
public final SessionLocal getSession() {
return session;
}
/**
* Find and collect all DbObjects, this Prepared depends on.
*
* @param dependencies collection of dependencies to populate
*/
public void collectDependencies(HashSet dependencies) {}
protected final Database getDatabase() {
return session.getDatabase();
}
/**
* Returns is this command can be repeated again on locking failure.
*
* @return is this command can be repeated again on locking failure
*/
public boolean isRetryable() {
return true;
}
}
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