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MCOL-271 empty strings should not be NULLs (#2794)

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This patch improves handling of NULLs in textual fields in ColumnStore.
Previously empty strings were considered NULLs and it could be a problem
if data scheme allows for empty strings. It was also one of major
reasons of behavior difference between ColumnStore and other engines in
MariaDB family.

Also, this patch fixes some other bugs and incorrect behavior, for
example, incorrect comparison for "column <= ''" which evaluates to
constant True for all purposes before this patch.
This commit is contained in:
Sergey Zefirov
2023-03-30 17:26:45 +01:00
committed by Roman Nozdrin
parent 0ea592da80
commit b53c231ca6
417 changed files with 12459 additions and 3520 deletions
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18
utils/funcexp/func_rpad.cpp
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@ -52,14 +52,12 @@ std::string Func_rpad::getStrVal(rowgroup::Row& row, FunctionParm& fp, bool& isN
{
CHARSET_INFO* cs = type.getCharset();
// The original string
const string& src = fp[0]->data()->getStrVal(row, isNull);
if (isNull)
const auto& src = fp[0]->data()->getStrVal(row, isNull);
if (src.isNull() || src.length() < 1)
return "";
if (src.empty() || src.length() == 0)
return src;
// binLen represents the number of bytes in src
size_t binLen = src.length();
const char* pos = src.c_str();
const char* pos = src.str();
const char* end = pos + binLen;
// strLen = the number of characters in src
size_t strLen = cs->numchars(pos, end);
@ -82,18 +80,18 @@ std::string Func_rpad::getStrVal(rowgroup::Row& row, FunctionParm& fp, bool& isN
}
// The pad characters.
const string* pad = &fPad;
string pad = fPad;
if (fp.size() > 2)
{
pad = &fp[2]->data()->getStrVal(row, isNull);
pad = fp[2]->data()->getStrVal(row, isNull).safeString("");
}
// binPLen represents the number of bytes in pad
size_t binPLen = pad->length();
const char* posP = pad->c_str();
size_t binPLen = pad.length();
const char* posP = pad.c_str();
// plen = the number of characters in pad
size_t plen = cs->numchars(posP, posP + binPLen);
if (plen == 0)
return src;
return src.safeString("");
size_t byteCount = (padLength + 1) * cs->mbmaxlen; // absolute maximun number of bytes
char* buf = new char[byteCount];