Java Oracle exception - "maximum number of expressions in a list is 1000"

Question

I am passing a list of Strings to my query(SQL query written) to fetch the required data. But I am getting this exception:

ora-01795 maximum number of expressions in a list is 1000

I checked that I have more than 1000 entries in the list passed to the query IN parameter.

Answer 1

this is a oracle limitation in the number of list pass in the query.

1. you will have to chop your query or
2. provide a subquery/join in the IN clause instead.

Answer 2

From dba-oracle.com:

ORA-01795: maximum number of expressions in a list is 1000 tips

Oracle Error Tips by Burleson Consulting (S. Karam)

The Oracle docs note this on the ora-01795 error*: ORA-01795 maximum number of expressions in a list is 1000 Cause: More than 254 columns or expressions were specified in a list. Action: Remove some of the expressions from the list. In the Oracle MOSC Forums, an Oracle user was attempting to find a way around error code ORA-01795. His question was answered by Reem Munakash of Oracle:

The limit in Oracle8 is 1000 expressions. There is a bug 495555, filed against the error text giving the wrong number (254). However, there may be a further restriction depending on the tool you are using. The 1000 expressions is within sqlplus.

The workaround would be to use a sub-query.

The bug regarding the error message is fixed in 8.1.5.

Answer 3

If you are able to convert your db-side logic from a query into a stored procedure, then you can pass longer arrays (collections) to it.

Here you can find a brief example how to do it. The link to the docs is outdated, so here's a link to the 9i docs http://docs.oracle.com/cd/B10500_01/java.920/a96654/oraarr.htm#1040124

import java.io.*;
import java.sql.*;
import oracle.sql.*;
import oracle.jdbc.driver.*;

public class ArrayDemo
{
    public static void passArray() throws SQLException
    {
        Connection conn =
            new OracleDriver().defaultConnection();

        int intArray[] = { 1,2,3,4,5,6 };

        ArrayDescriptor descriptor =
            ArrayDescriptor.createDescriptor( "NUM_ARRAY", conn );

        ARRAY array_to_pass =
            new ARRAY( descriptor, conn, intArray );

        OraclePreparedStatement ps =
            (OraclePreparedStatement)conn.prepareStatement
            ( "begin give_me_an_array(:x); end;" );

        ps.setARRAY( 1, array_to_pass );

        ps.execute();

    }
}

and the SQL part

create or replace type NUM_ARRAY as table of number;

create or replace
procedure give_me_an_array( p_array in num_array )
as
begin
    for i in 1 .. p_array.count
    loop
        dbms_output.put_line( p_array(i) );
    end loop;
end;

Answer 4

you can create a temporary table, and insert the values you want use in your IN statement, and join the temporary table with your real table. more information about temporary tables.

Answer 5

I solved this by breaking the list into batch of size 1000 and joining it using OR.

e.g. eid[] array of ids.

If I want to execute this query,

String sql = select * from employee where some conditions and empid in(eid)

I have re-written this query by writing a small piece of code:

String sql = select * from employee where some conditions and ( 
                             empid in(empid[0...999]) OR
                             empid in(empid[1000...1999]) OR
                             empid in(empid[2000...2999]) OR .... );

Dealing with this error while using hibernate, you have to tackle this issue by chopping the list into batch of 100 and then join the individual results (as shown in the query above).

I don't think that it's a limitation of hibernate for not handling this issue, because it may be the case that this issue is not a case of another DB like MySQL or DB2. Hibernate is a cross-DB ORM framework.

Answer 6

You cant have a list with more than 1000 elements in a single "where" condition if you are working with Oracle DB. So you can chop down your "where" condition in multiple "where" conditions and join them with "or" clause.

If you are using hibernate Criteria, you can use below Java method to do this. Just replace your code where ever you used

criteria.add(Restrictions.in(propertyName, mainList));

with

addCriteriaIn(propertyName, mainList, criteria);

which the method is :

 private void addCriteriaIn (String propertyName, List<?> list,Criteria criteria)
  {
    Disjunction or = Restrictions.disjunction();
    if(list.size()>1000)
    {        
      while(list.size()>1000)
      {
        List<?> subList = list.subList(0, 1000);
        or.add(Restrictions.in(propertyName, subList));
        list.subList(0, 1000).clear();
      }
    }
    or.add(Restrictions.in(propertyName, list));
    criteria.add(or);
  }

Answer 7

Using Java Hibernate, to solve this problem I decided to change the Hibernate-core JAR. I madea a helper class to split an expression in more joins like: ... t.column IN (: list_1) OR t.column IN (: list_2) ... , Then I changed AbstractQueryImpl.expandParameterList method from hibernate to call my method if the collection exceeds the limit.
My hibernate-core version is 3.6.10.Final, but it work fine and for 4.x versions - I tested it.
My code is tested for next cases:

  where t.id in (:idList)
  where (t.id in (:idList))
  where ((t.id) in (:idList))
  where 1=1 and t.id in (:idList)
  where 1=1 and (t.id in (:idList))
  where 1=1 and(t.id) in (:idList)
  where 1=1 and((t.id) in (:idList))
  where 1=1 and(t.id in (:idList))

  where t.id not in (:idList)
  where (t.id not in (:idList))
  where ((t.id) not in (:idList))

AbstractQueryImpl.expandParameterList :

private String expandParameterList(String query, String name, TypedValue typedList, Map namedParamsCopy) {
    Collection vals = (Collection) typedList.getValue();
    Type type = typedList.getType();

    boolean isJpaPositionalParam = parameterMetadata.getNamedParameterDescriptor( name ).isJpaStyle();
    String paramPrefix = isJpaPositionalParam ? "?" : ParserHelper.HQL_VARIABLE_PREFIX;
    String placeholder =
            new StringBuffer( paramPrefix.length() + name.length() )
                    .append( paramPrefix ).append(  name )
                    .toString();

    if ( query == null ) {
        return query;
    }
    int loc = query.indexOf( placeholder );

    if ( loc < 0 ) {
        return query;
    }

    String beforePlaceholder = query.substring( 0, loc );
    String afterPlaceholder =  query.substring( loc + placeholder.length() );

    // check if placeholder is already immediately enclosed in parentheses
    // (ignoring whitespace)
    boolean isEnclosedInParens =
            StringHelper.getLastNonWhitespaceCharacter( beforePlaceholder ) == '(' &&
                    StringHelper.getFirstNonWhitespaceCharacter( afterPlaceholder ) == ')';

    if ( vals.size() == 1  && isEnclosedInParens ) {
        // short-circuit for performance when only 1 value and the
        // placeholder is already enclosed in parentheses...
        namedParamsCopy.put( name, new TypedValue( type, vals.iterator().next(), session.getEntityMode() ) );
        return query;
    }

    // *** changes by Vasile Bors for HHH-1123 ***
    // case vals.size() > 1000
    if ((vals.size() >= InExpressionExpander.MAX_ALLOWED_PER_INEXPR) && isEnclosedInParens) {

        InExpressionExpander inExpressionExpander = new InExpressionExpander(beforePlaceholder, afterPlaceholder);
        if(inExpressionExpander.isValidInOrNotInExpression()){

            List<String> list = new ArrayList<String>( vals.size() );
            Iterator iter = vals.iterator();
            int i = 0;
            String alias;
            while ( iter.hasNext() ) {
                alias = ( isJpaPositionalParam ? 'x' + name : name ) + i++ + '_';
                namedParamsCopy.put( alias, new TypedValue( type, iter.next(), session.getEntityMode() ) );
                list.add(ParserHelper.HQL_VARIABLE_PREFIX + alias );
            }

            String expandedExpression = inExpressionExpander.expandExpression(list);
            if(expandedExpression != null){
                return expandedExpression;
            }
        }
    }
    // *** end changes by Vasile Bors for HHH-1123 ***

    StringBuffer list = new StringBuffer(16);
    Iterator iter = vals.iterator();
    int i = 0;
    while (iter.hasNext()) {
        String alias = (isJpaPositionalParam ? 'x' + name : name) + i++ + '_';
        namedParamsCopy.put(alias, new TypedValue(type, iter.next(), session.getEntityMode()));
        list.append(ParserHelper.HQL_VARIABLE_PREFIX).append(alias);
        if (iter.hasNext()) {
            list.append(", ");
        }
    }

    return StringHelper.replace(
            beforePlaceholder,
            afterPlaceholder,
            placeholder.toString(),
            list.toString(),
            true,
            true
    );
}

My helper class InExpressionExpander:

package org.hibernate.util;

import org.hibernate.QueryException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Iterator;
import java.util.List;
import java.util.Stack;

/**
 * Utility class for expand Hql and Sql IN expressions with a parameter with more than IN expression limit size (HHH-1123).
 * <br/>
 * It work for expression with formats:
 * <pre>
 *
 * where t.id in (:idList)
 * where (t.id in (:idList))
 * where ((t.id) in (:idList))
 * where 1=1 and t.id in (:idList)
 * where 1=1 and (t.id in (:idList))
 * where 1=1 and(t.id) in (:idList)
 * where 1=1 and((t.id) in (:idList))
 * where 1=1 and(t.id in (:idList))
 *
 * where t.id not in (:idList)
 * where (t.id not in (:idList))
 * where ((t.id) not in (:idList))
 * </pre>
 * <p/>
 * Example:
 * <pre>
 * select t.id from tableOrEntity t where t.id IN (:idList)
 * </pre
 *
 * @author Vasile Bors
 * @since 13/12/2015.
 */
public class InExpressionExpander {
    private static final Logger log = LoggerFactory.getLogger(InExpressionExpander.class);

    public static final  int MAX_ALLOWED_PER_INEXPR = 1000;
    private static final int MAX_PARAMS_PER_INEXPR  = 500;

    private Stack<String> stackExpr = new Stack<String>();
    private StringBuilder toWalkQuery;

    private final String beforePlaceholder;
    private final String afterPlaceholder;
    private boolean wasChecked         = false;
    private boolean isEnclosedInParens = false;
    private boolean isInExpr           = false;
    private boolean isNotInExpr        = false;

    public InExpressionExpander(String beforePlaceholder, String afterPlaceholder) {
        this.toWalkQuery = new StringBuilder(beforePlaceholder);

        this.beforePlaceholder = beforePlaceholder;
        this.afterPlaceholder = afterPlaceholder;
    }

    public boolean isValidInOrNotInExpression() {
        if (!wasChecked) {
            String lastExpr = extractLastExpression();
            if ("(".equals(lastExpr)) {
                isEnclosedInParens = true;
                lastExpr = extractLastExpression();
            }
            isInExpr = "in".equalsIgnoreCase(lastExpr);
        }

        wasChecked = true;
        return isInExpr;
    }

    public String expandExpression(List paramList) {
        if (isValidInOrNotInExpression()) {

            final String lastExpr = extractLastExpression(false);

            if ("not".equalsIgnoreCase(lastExpr)) {
                isNotInExpr = true;
                extractLastExpression(); //extract "not" and consume it
            }

            extractColumnForInExpression();

            StringBuilder exprPrefixBuilder = new StringBuilder();
            for (int i = stackExpr.size() - 1; i > -1; i--) {
                exprPrefixBuilder.append(stackExpr.get(i)).append(' ');
            }
            if (!isEnclosedInParens) {
                exprPrefixBuilder.append('(');
            }

            String expandedExpression = expandInExpression(exprPrefixBuilder, paramList);
            String beforeExpression = getBeforeExpression();
            String afterExpression = getAfterExpression();

            String expandedQuery = new StringBuilder(beforeExpression).append(expandedExpression)
                    .append(afterExpression)
                    .toString();

            if (log.isDebugEnabled()) {
                log.debug(
                        "Query was changed to prevent exception for maximum number of expression in a list. Expanded IN expression query:\n {}",
                        expandedExpression);

                log.debug("Expanded query:\n {}", expandedQuery);
            }

            return expandedQuery;
        }

        log.error("Illegal call of InExpressionExpander.expandExpression() without IN expression.");
        return null;
    }

    private String expandInExpression(StringBuilder exprPrefixBuilder, List values) {

        String joinExpr = isNotInExpr ? ") and " : ") or ";
        StringBuilder expr = new StringBuilder(16);
        Iterator iter = values.iterator();
        int i = 0;
        boolean firstExpr = true;
        while (iter.hasNext()) {
            if (firstExpr || i % MAX_PARAMS_PER_INEXPR == 0) {
                //close previous expression and start new expression
                if (!firstExpr) {
                    expr.append(joinExpr);
                } else {
                    firstExpr = false;
                }
                expr.append(exprPrefixBuilder);
            } else {
                expr.append(", ");
            }
            expr.append(iter.next());
            i++;
        }

        expr.append(')');// close for last in expression

        return expr.toString();
    }

    /**
     * Method extract last expression parsed by space from toWalkQuery and remove it from toWalkQuery;<br/>
     * If expression has brackets it will return al content between brackets and it will add additional space to adjust splitting by space.
     *
     * @return last expression from toWalkQuery
     */
    private String extractLastExpression() {
        return extractLastExpression(true);
    }

    /**
     * Method extract last expression parsed by space from toWalkQuery, remove it from toWalkQuery if is consume = true;<br/>
     * If expression has brackets it will return al content between brackets and it will add additional space to adjust splitting by space.
     *
     * @param consum if true  the method will extract and remove last expression from toWalkQuery
     * @return last expression from toWalkQuery
     */
    private String extractLastExpression(final boolean consum) {
        int lastIndex = this.toWalkQuery.length() - 1;
        String lastExpr;
        int exprSeparatorIndex = this.toWalkQuery.lastIndexOf(" ");
        if (lastIndex == exprSeparatorIndex) { //remove last space from the end
            this.toWalkQuery.delete(exprSeparatorIndex, this.toWalkQuery.length());
            return extractLastExpression(consum);
        } else {
            lastExpr = this.toWalkQuery.substring(exprSeparatorIndex + 1, this.toWalkQuery.length());

            if (lastExpr.length() > 1) {
                if (lastExpr.endsWith(")")) {
                    //if parens are closed at the end we need to find where it is open
                    int opensParens = 0;
                    int closedParens = 0;
                    int startExprIndex = -1;

                    char c;
                    for (int i = lastExpr.length() - 1; i > -1; i--) {
                        c = lastExpr.charAt(i);
                        if (c == ')') {
                            closedParens++;
                        } else if (c == '(') {
                            opensParens++;
                        }

                        if (closedParens == opensParens) {
                            startExprIndex = i;
                            break;
                        }
                    }

                    if (startExprIndex > -1) {
                        lastExpr = lastExpr.substring(startExprIndex, lastExpr.length());
                        exprSeparatorIndex = exprSeparatorIndex + startExprIndex
                                + 1; // +1 because separator is not space and don't must be deleted
                    }
                } else if (lastExpr.contains("(")) {
                    int parentsIndex = exprSeparatorIndex + lastExpr.indexOf('(') + 1;
                    this.toWalkQuery.replace(parentsIndex, parentsIndex + 1, " ( ");
                    return extractLastExpression(consum);
                }
            }

            if (consum) {
                this.toWalkQuery.delete(exprSeparatorIndex, this.toWalkQuery.length());
            }
        }

        if (consum) {
            stackExpr.push(lastExpr);
        }

        return lastExpr;
    }

    private String extractColumnForInExpression() {
        String column = extractLastExpression();

        String beforeColumn = extractLastExpression(false);
        long pointIndx = beforeColumn.lastIndexOf('.');
        if (pointIndx > -1) {
            if (pointIndx == (beforeColumn.length() - 1)) {
                throw new QueryException(
                        "Invalid column format: " + beforeColumn + ' ' + column
                                + " . Remove space from column!");
            }
        }
        return column;
    }

    private String getBeforeExpression() {
        return this.toWalkQuery + " (";
    }

    private String getAfterExpression() {
        if (StringHelper.getFirstNonWhitespaceCharacter(afterPlaceholder) == ')') {
            return afterPlaceholder;
        }
        return afterPlaceholder + ") ";
    }
}

I am happy to receive any suggestions for improving this solution.