DbtuxCmp.cpp
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上传日期:2022-05-23
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- /* Copyright (C) 2003 MySQL AB
- 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; either version 2 of the License, or
- (at your option) any later version.
- 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
- #define DBTUX_CMP_CPP
- #include "Dbtux.hpp"
- /*
- * Search key vs node prefix or entry
- *
- * The comparison starts at given attribute position. The position is
- * updated by number of equal initial attributes found. The entry data
- * may be partial in which case CmpUnknown may be returned.
- */
- int
- Dbtux::cmpSearchKey(const Frag& frag, unsigned& start, ConstData searchKey, ConstData entryData, unsigned maxlen)
- {
- const unsigned numAttrs = frag.m_numAttrs;
- const DescEnt& descEnt = getDescEnt(frag.m_descPage, frag.m_descOff);
- // number of words of attribute data left
- unsigned len2 = maxlen;
- // skip to right position in search key only
- for (unsigned i = 0; i < start; i++) {
- jam();
- searchKey += AttributeHeaderSize + searchKey.ah().getDataSize();
- }
- int ret = 0;
- while (start < numAttrs) {
- if (len2 <= AttributeHeaderSize) {
- jam();
- ret = NdbSqlUtil::CmpUnknown;
- break;
- }
- len2 -= AttributeHeaderSize;
- if (! searchKey.ah().isNULL()) {
- if (! entryData.ah().isNULL()) {
- jam();
- // current attribute
- const DescAttr& descAttr = descEnt.m_descAttr[start];
- // full data size
- const unsigned size1 = AttributeDescriptor::getSizeInWords(descAttr.m_attrDesc);
- ndbrequire(size1 != 0 && size1 == entryData.ah().getDataSize());
- const unsigned size2 = min(size1, len2);
- len2 -= size2;
- // compare
- NdbSqlUtil::Cmp* const cmp = c_sqlCmp[start];
- const Uint32* const p1 = &searchKey[AttributeHeaderSize];
- const Uint32* const p2 = &entryData[AttributeHeaderSize];
- ret = (*cmp)(0, p1, p2, size1, size2);
- if (ret != 0) {
- jam();
- break;
- }
- } else {
- jam();
- // not NULL > NULL
- ret = +1;
- break;
- }
- } else {
- if (! entryData.ah().isNULL()) {
- jam();
- // NULL < not NULL
- ret = -1;
- break;
- }
- }
- searchKey += AttributeHeaderSize + searchKey.ah().getDataSize();
- entryData += AttributeHeaderSize + entryData.ah().getDataSize();
- start++;
- }
- return ret;
- }
- /*
- * Scan bound vs node prefix or entry.
- *
- * Compare lower or upper bound and index entry data. The entry data
- * may be partial in which case CmpUnknown may be returned. Otherwise
- * returns -1 if the bound is to the left of the entry and +1 if the
- * bound is to the right of the entry.
- *
- * The routine is similar to cmpSearchKey, but 0 is never returned.
- * Suppose all attributes compare equal. Recall that all bounds except
- * possibly the last one are non-strict. Use the given bound direction
- * (0-lower 1-upper) and strictness of last bound to return -1 or +1.
- *
- * Following example illustrates this. We are at (a=2, b=3).
- *
- * dir bounds strict return
- * 0 a >= 2 and b >= 3 no -1
- * 0 a >= 2 and b > 3 yes +1
- * 1 a <= 2 and b <= 3 no +1
- * 1 a <= 2 and b < 3 yes -1
- */
- int
- Dbtux::cmpScanBound(const Frag& frag, unsigned dir, ConstData boundInfo, unsigned boundCount, ConstData entryData, unsigned maxlen)
- {
- const DescEnt& descEnt = getDescEnt(frag.m_descPage, frag.m_descOff);
- // direction 0-lower 1-upper
- ndbrequire(dir <= 1);
- // number of words of data left
- unsigned len2 = maxlen;
- // in case of no bounds, init last type to something non-strict
- unsigned type = 4;
- while (boundCount != 0) {
- if (len2 <= AttributeHeaderSize) {
- jam();
- return NdbSqlUtil::CmpUnknown;
- }
- len2 -= AttributeHeaderSize;
- // get and skip bound type (it is used after the loop)
- type = boundInfo[0];
- boundInfo += 1;
- if (! boundInfo.ah().isNULL()) {
- if (! entryData.ah().isNULL()) {
- jam();
- // current attribute
- const unsigned index = boundInfo.ah().getAttributeId();
- ndbrequire(index < frag.m_numAttrs);
- const DescAttr& descAttr = descEnt.m_descAttr[index];
- ndbrequire(entryData.ah().getAttributeId() == descAttr.m_primaryAttrId);
- // full data size
- const unsigned size1 = boundInfo.ah().getDataSize();
- ndbrequire(size1 != 0 && size1 == entryData.ah().getDataSize());
- const unsigned size2 = min(size1, len2);
- len2 -= size2;
- // compare
- NdbSqlUtil::Cmp* const cmp = c_sqlCmp[index];
- const Uint32* const p1 = &boundInfo[AttributeHeaderSize];
- const Uint32* const p2 = &entryData[AttributeHeaderSize];
- int ret = (*cmp)(0, p1, p2, size1, size2);
- if (ret != 0) {
- jam();
- return ret;
- }
- } else {
- jam();
- // not NULL > NULL
- return +1;
- }
- } else {
- jam();
- if (! entryData.ah().isNULL()) {
- jam();
- // NULL < not NULL
- return -1;
- }
- }
- boundInfo += AttributeHeaderSize + boundInfo.ah().getDataSize();
- entryData += AttributeHeaderSize + entryData.ah().getDataSize();
- boundCount -= 1;
- }
- // all attributes were equal
- const int strict = (type & 0x1);
- return (dir == 0 ? (strict == 0 ? -1 : +1) : (strict == 0 ? +1 : -1));
- }