dbcon/mysql/ha_in_sub.cpp

/* Copyright (C) 2014 InfiniDB, Inc.
   Copyright (C) 2016 MariaDB Corporation

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; version 2 of
   the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

/***********************************************************************
*   $Id: ha_in_sub.cpp 6407 2010-03-26 19:36:56Z zzhu $
*
*
***********************************************************************/
/** @file */
/** class InSub definition */

#include <my_config.h>
#include <stdint.h>
//#define NDEBUG
#include <cassert>
#include <vector>
using namespace std;

#include "idb_mysql.h"

#include "parsetree.h"
#include "logicoperator.h"
#include "existsfilter.h"
#include "simplescalarfilter.h"
#include "selectfilter.h"
#include "simplefilter.h"
#include "predicateoperator.h"
#include "rowcolumn.h"
using namespace execplan;

#include "errorids.h"
using namespace logging;

#include "ha_subquery.h"

namespace cal_impl_if
{
extern void parse_item (Item* item, vector<Item_field*>& field_vec, bool& hasNonSupportItem, uint16& parseInfo);

void makeAntiJoin(const ParseTree* n)
{
    TreeNode* tn = n->data();
    SimpleFilter* sf = dynamic_cast<SimpleFilter*>(tn);

    if (!sf)
        return;

    uint64_t lJoinInfo = sf->lhs()->joinInfo();

    if (lJoinInfo & JOIN_SEMI)
    {
        lJoinInfo &= ~JOIN_SEMI;
        lJoinInfo |= JOIN_ANTI;

        if (lJoinInfo & JOIN_NULLMATCH_CANDIDATE)
            lJoinInfo |= JOIN_NULL_MATCH;

        sf->lhs()->joinInfo(lJoinInfo);
    }

    uint64_t rJoinInfo = sf->rhs()->joinInfo();

    if (rJoinInfo & JOIN_SEMI)
    {
        rJoinInfo &= ~JOIN_SEMI;
        rJoinInfo |= JOIN_ANTI;

        if (rJoinInfo & JOIN_NULLMATCH_CANDIDATE)
            rJoinInfo |= JOIN_NULL_MATCH;

        sf->rhs()->joinInfo(rJoinInfo);
    }
}

InSub::InSub(gp_walk_info& gwip) : WhereSubQuery(gwip)
{}

InSub::InSub(gp_walk_info& gwip, Item_func* func) :
    WhereSubQuery(gwip, func)
{}

InSub::InSub(const InSub& rhs) :
    WhereSubQuery(rhs.gwip(), rhs.fColumn, rhs.fSub, rhs.fFunc)
{}

InSub::~InSub()
{}

/** MySQL transform (NOT) IN subquery to (NOT) EXIST
 *
 */
execplan::ParseTree* InSub::transform()
{
    if (!fFunc)
        return NULL;

    // @todo need to handle scalar IN and BETWEEN specially
    // this blocks handles only one subselect scalar
    // arg[0]: column | arg[1]: subselect
    //assert (fFunc->argument_count() == 2 && fGwip.rcWorkStack.size() >= 2);
    if (fFunc->argument_count() != 2 || fGwip.rcWorkStack.size() < 2)
    {
        fGwip.fatalParseError = true;
        fGwip.parseErrorText = "Unsupported item in IN subquery";
        return NULL;
    }

    ReturnedColumn* rhs = fGwip.rcWorkStack.top();
    fGwip.rcWorkStack.pop();
    delete rhs;
    ReturnedColumn* lhs = fGwip.rcWorkStack.top();
    fGwip.rcWorkStack.pop();
    delete lhs;

    fSub = (Item_subselect*)(fFunc->arguments()[1]);
    idbassert(fSub && fFunc);

    SCSEP csep (new CalpontSelectExecutionPlan());
    csep->sessionID(fGwip.sessionid);
    csep->location(CalpontSelectExecutionPlan::WHERE);
    csep->subType (CalpontSelectExecutionPlan::IN_SUBS);

    // gwi for the sub query
    gp_walk_info gwi;
    gwi.thd = fGwip.thd;
    gwi.subQuery = this;

    // @4827 merge table list to gwi in case there is FROM sub to be referenced
    // in the FROM sub
    gwi.derivedTbCnt = fGwip.derivedTbList.size();
    uint32_t tbCnt = fGwip.tbList.size();

    gwi.tbList.insert(gwi.tbList.begin(), fGwip.tbList.begin(), fGwip.tbList.end());
    gwi.derivedTbList.insert(gwi.derivedTbList.begin(), fGwip.derivedTbList.begin(), fGwip.derivedTbList.end());

    if (getSelectPlan(gwi, *(fSub->get_select_lex()), csep, false) != 0)
    {
        fGwip.fatalParseError = true;

        if (gwi.fatalParseError && !gwi.parseErrorText.empty())
            fGwip.parseErrorText = gwi.parseErrorText;
        else
            fGwip.parseErrorText = "Error occured in InSub::transform()";

        return NULL;
    }

    // remove outer query tables
    CalpontSelectExecutionPlan::TableList tblist;

    if (csep->tableList().size() >= tbCnt)
        tblist.insert(tblist.begin(), csep->tableList().begin() + tbCnt, csep->tableList().end());

    CalpontSelectExecutionPlan::SelectList derivedTbList;

    if (csep->derivedTableList().size() >= gwi.derivedTbCnt)
        derivedTbList.insert(derivedTbList.begin(),
                             csep->derivedTableList().begin() + gwi.derivedTbCnt,
                             csep->derivedTableList().end());

    csep->tableList(tblist);
    csep->derivedTableList(derivedTbList);

    ExistsFilter* subFilter = new ExistsFilter();
    subFilter->sub(csep);

    if (gwi.subQuery->correlated())
        subFilter->correlated(true);
    else
        subFilter->correlated(false);

    if (fGwip.clauseType == HAVING && subFilter->correlated())
    {
        fGwip.fatalParseError = true;
        fGwip.parseErrorText = logging::IDBErrorInfo::instance()->errorMsg(logging::ERR_NON_SUPPORT_HAVING);
    }

    fGwip.subselectList.push_back(csep);
    return new ParseTree(subFilter);
}

/**
 * Handle MySQL's plugin functions
 * This is mostly for handling the null related functions that MySQL adds to the execution plan
 */
void InSub::handleFunc(gp_walk_info* gwip, Item_func* func)
{
    if (func->functype() == Item_func::TRIG_COND_FUNC || func->functype() == Item_func::COND_OR_FUNC)
    {
        // purpose: remove the isnull() function from the parsetree in ptWorkStack.
        // IDB handles the null semantics in the join operation
        // trigcond(or_cond) is the only form we recognize for now
        if (func->argument_count() > 2)
        {
            fGwip.fatalParseError = true;
            fGwip.parseErrorText = "Unsupported item in IN subquery";
            return;
        }

        Item_cond* cond;

        if (func->functype() == Item_func::TRIG_COND_FUNC)
        {
            Item* item;

            if (func->arguments()[0]->type() == Item::REF_ITEM)
                item = (Item_ref*)(func->arguments()[0])->real_item();
            else
                item = func->arguments()[0];

            cond = (Item_cond*)(item);
        }
        else
        {
            cond = (Item_cond*)(func);
        }

        if (cond->functype() == Item_func::COND_OR_FUNC)
        {
            // (cache=item) case. do nothing. ignore trigcond()?
            if (cond->argument_list()->elements == 1)
                return;

            if (cond->argument_list()->elements == 2)
            {
                // don't know how to deal with this. don't think it's a fatal error either.
                if (gwip->ptWorkStack.empty())
                    return;

                ParseTree* pt = gwip->ptWorkStack.top();

                if (!pt->left() || !pt->right())
                    return;

                SimpleFilter* lsf = dynamic_cast<SimpleFilter*>(pt->left()->data());
                SimpleFilter* rsf = dynamic_cast<SimpleFilter*>(pt->right()->data());
                SimpleFilter* sf = nullptr;

                if (!lsf || !rsf)
                    return;

                if ((lsf->op()->op() == execplan::OP_ISNULL ||
                     lsf->op()->op() == execplan::OP_ISNOTNULL) &&
                    rsf->op()->op() == execplan::OP_EQ)
                {
                    // (cache=item or isnull(item)) case. remove "or isnull()"
                    if ((rsf->lhs()->joinInfo() & JOIN_CORRELATED ||
                         rsf->rhs()->joinInfo() & JOIN_CORRELATED) &&
                        lsf->op()->op() == execplan::OP_ISNULL)
                    {
                        delete lsf;
                        sf = rsf;
                        pt = pt->right();
                    }
                    else
                    {
                        ParseTree* temp = pt->left();
                        pt->left(pt->right());
                        pt->right(temp);
                        return;
                    }
                }
                else
                {
                    return;
                }

                // set NULLMATCH for both operand. It's really a setting for the join.
                // should only set NULLMATCH when the subtype is NOT_IN. for some IN subquery
                // with aggregation column, MySQL inefficiently convert to:
                // (cache=item or item is null) and item is not null, which is equivalent to
                // cache = item. Do not set NULLMATCH for this case.
                // Because we don't know IN or NOTIN yet, set candidate bit and switch to NULLMATCH
                // later in handleNot function.
                if (sf->lhs()->joinInfo() & JOIN_CORRELATED)
                {
                    sf->lhs()->joinInfo(sf->lhs()->joinInfo() | JOIN_NULLMATCH_CANDIDATE);
                }

                if (sf->rhs()->joinInfo() & JOIN_CORRELATED)
                {
                    sf->rhs()->joinInfo(sf->rhs()->joinInfo() | JOIN_NULLMATCH_CANDIDATE);
                }

                gwip->ptWorkStack.pop();
                gwip->ptWorkStack.push(pt);
            }
        }
        else if (cond->functype() == Item_func::EQ_FUNC)
        {
            // not in (select const ...)
            if (gwip->ptWorkStack.empty())
                return;

            ParseTree* pt = gwip->ptWorkStack.top();
            SimpleFilter* sf = dynamic_cast<SimpleFilter*>(pt->data());

            if (!sf || sf->op()->op() != execplan::OP_EQ)
                return;

            if (sf->lhs()->joinInfo() & JOIN_CORRELATED)
                sf->lhs()->joinInfo(sf->lhs()->joinInfo() | JOIN_NULLMATCH_CANDIDATE);

            if (sf->rhs()->joinInfo() & JOIN_CORRELATED)
                sf->rhs()->joinInfo(sf->rhs()->joinInfo() | JOIN_NULLMATCH_CANDIDATE);
        }
    }
}

/**
 * This is invoked when a NOT function is got. It's usually the case NOT<IN optimizer>
 * This function will simple turn the semi join to anti join
 *
 */
void InSub::handleNot()
{
    ParseTree* pt = fGwip.ptWorkStack.top();
    ExistsFilter* subFilter = dynamic_cast<ExistsFilter*>(pt->data());
    idbassert(subFilter);
    subFilter->notExists(true);
    SCSEP csep = subFilter->sub();
    const ParseTree* ptsub = csep->filters();

    if (ptsub)
        ptsub->walk(makeAntiJoin);

    ptsub = csep->having();

    if (ptsub)
        ptsub->walk(makeAntiJoin);
}

}