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be less annoying about sysvar-based table attributes

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do not *always* add them to the create table definition,
but only when a sysvar value is different from a default.

also, when adding them - don't quote numbers
This commit is contained in:
Sergei Golubchik
2015-04-10 02:36:54 +02:00
parent eb29a63e45
commit dd8f931957
6 changed files with 88 additions and 36 deletions
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60
sql/create_options.cc
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@ -297,8 +297,7 @@ bool parse_option_list(THD* thd, handlerton *hton, void *option_struct_arg,
(uchar*)val->name.str, val->name.length))
continue;
seen=true;
/* skip duplicates (see engine_option_value constructor above) */
if (val->parsed && !val->value.str)
continue;
@ -306,39 +305,58 @@ bool parse_option_list(THD* thd, handlerton *hton, void *option_struct_arg,
*option_struct, suppress_warning || val->parsed, root))
DBUG_RETURN(TRUE);
val->parsed= true;
seen=true;
break;
}
if (!seen)
if (!seen || (opt->var && !last->value.str))
{
LEX_STRING default_val= null_lex_str;
/*
If it's CREATE/ALTER TABLE parsing mode (options are created in the
transient thd->mem_root, not in the long living TABLE_SHARE::mem_root),
and variable-backed option was not explicitly set.
Okay, here's the logic for sysvar options:
1. When we parse CREATE TABLE and sysvar option was not explicitly
mentioned we add it to the list as if it was specified with the
*current* value of the underlying sysvar.
2. But only if the underlying sysvar value is different from the
sysvar's default.
3. If it's ALTER TABLE and the sysvar option was not explicitly
mentioned - do nothing, do not add it to the list.
4. But if it was ALTER TABLE with sysvar option = DEFAULT, we
add it to the list (under the same condition #2).
5. If we're here parsing the option list from the .frm file
for a normal open_table() and the sysvar option was not there -
do not add it to the list (makes no sense anyway) and
use the *default* value of the underlying sysvar. Because
sysvar value can change, but it should not affect existing tables.
If it's not create, but opening of the existing frm (that was,
probably, created with the older version of the storage engine and
does not have this option stored), we take the *default* value of the
sysvar, not the *current* value. Because we don't want to have
different option values for the same table if it's opened many times.
This is how it's implemented: the current sysvar value is added
to the list if suppress_warning is FALSE (meaning a table is created,
that is CREATE TABLE or ALTER TABLE) and it's actually a CREATE TABLE
command or it's an ALTER TABLE and the option was seen (=DEFAULT).
Note that if the option was set explicitly (not =DEFAULT) it wouldn't
have passes the if() condition above.
*/
if (root == thd->mem_root && opt->var)
if (!suppress_warning && opt->var &&
(thd->lex->sql_command == SQLCOM_CREATE_TABLE || seen))
{
// take a value from the variable and add it to the list
sys_var *sysvar= find_hton_sysvar(hton, opt->var);
DBUG_ASSERT(sysvar);
char buf[256];
String sbuf(buf, sizeof(buf), system_charset_info), *str;
if ((str= sysvar->val_str(&sbuf, thd, OPT_SESSION, &null_lex_str)))
if (!sysvar->session_is_default(thd))
{
LEX_STRING name= { const_cast<char*>(opt->name), opt->name_length };
default_val.str= strmake_root(root, str->ptr(), str->length());
default_val.length= str->length();
val= new (root) engine_option_value(name, default_val, true,
option_list, &last);
val->parsed= true;
char buf[256];
String sbuf(buf, sizeof(buf), system_charset_info), *str;
if ((str= sysvar->val_str(&sbuf, thd, OPT_SESSION, &null_lex_str)))
{
LEX_STRING name= { const_cast<char*>(opt->name), opt->name_length };
default_val.str= strmake_root(root, str->ptr(), str->length());
default_val.length= str->length();
val= new (root) engine_option_value(name, default_val,
opt->type != HA_OPTION_TYPE_ULL, option_list, &last);
val->parsed= true;
}
}
}
set_one_value(opt, thd, &default_val, *option_struct,