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pgbench: Remove \cset 

Partial revert of commit 6260cc550b, "pgbench: add \cset and \gset
commands".

While \gset is widely considered a useful and necessary tool for user-
defined benchmarks, \cset does not have as much value, and its
implementation was considered "not to be up to project standards"
(though I, Álvaro, can't quite understand exactly how).  Therefore,
remove \cset.

Author: Fabien Coelho
Discussion: https://postgr.es/m/alpine.DEB.2.21.1903230716030.18811@lancre
Discussion: https://postgr.es/m/201901101900.mv7zduch6sad@alvherre.pgsql
This commit is contained in:
Alvaro Herrera 2019-03-25 12:16:07 -03:00
parent 6f97457e0d
commit 25ee70511e
6 changed files with 56 additions and 238 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
doc/src/sgml/ref/pgbench.sgml
View File

@ -963,48 +963,6 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
</para>
<variablelist>
<varlistentry id='pgbench-metacommand-cset'>
<term>
<literal>\cset [<replaceable>prefix</replaceable>]</literal>
</term>
<listitem>
<para>
This command may be used to end SQL queries, replacing an embedded
semicolon (<literal>\;</literal>) within a compound SQL command.
</para>
<para>
When this command is used, the preceding SQL query is expected to
return one row, the columns of which are stored into variables named after
column names, and prefixed with <replaceable>prefix</replaceable> if provided.
</para>
<para>
The following example sends four queries as one compound SQL command,
inducing one message sent at the protocol level.
The result of the first query is stored into variable <replaceable>one</replaceable>,
the results of the third query are stored into variables <replaceable>z_three</replaceable>
and <replaceable>z_four</replaceable>,
whereas the results of the other queries are discarded.
<programlisting>
-- compound of four queries
SELECT 1 AS one \cset
SELECT 2 AS two \;
SELECT 3 AS three, 4 AS four \cset z_
SELECT 5;
</programlisting>
</para>
<note>
<para>
<literal>\cset</literal> does not work when empty SQL queries appear
within a compound SQL command.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry id='pgbench-metacommand-gset'>
<term>
<literal>\gset [<replaceable>prefix</replaceable>]</literal>
@ -1012,8 +970,8 @@ SELECT 5;
<listitem>
<para>
This command may be used to end SQL queries, replacing a final semicolon
(<literal>;</literal>).
This command may be used to end SQL queries, taking the place of the
terminating semicolon (<literal>;</literal>).
</para>
<para>
@ -1026,7 +984,7 @@ SELECT 5;
The following example puts the final account balance from the first query
into variable <replaceable>abalance</replaceable>, and fills variables
<replaceable>p_two</replaceable> and <replaceable>p_three</replaceable>
with integers from the last query.
with integers from the third query.
The result of the second query is discarded.
<programlisting>
UPDATE pgbench_accounts
@ -1038,13 +996,6 @@ SELECT 1 \;
SELECT 2 AS two, 3 AS three \gset p_
</programlisting>
</para>
<note>
<para>
<literal>\gset</literal> does not work when empty SQL queries appear
within a compound SQL command.
</para>
</note>
</listitem>
</varlistentry>

165
src/bin/pgbench/pgbench.c
View File

@ -490,7 +490,6 @@ typedef enum MetaCommand
META_SETSHELL, /* \setshell */
META_SHELL, /* \shell */
META_SLEEP, /* \sleep */
META_CSET, /* \cset */
META_GSET, /* \gset */
META_IF, /* \if */
META_ELIF, /* \elif */
@ -521,11 +520,9 @@ static const char *QUERYMODE[] = {"simple", "extended", "prepared"};
* argv Command arguments, the first of which is the command or SQL
* string itself. For SQL commands, after post-processing
* argv[0] is the same as 'lines' with variables substituted.
* nqueries In a multi-command SQL line, the number of queries.
* varprefix SQL commands terminated with \gset or \cset have this set
* varprefix SQL commands terminated with \gset have this set
* to a non NULL value. If nonempty, it's used to prefix the
* variable name that receives the value.
* varprefix_max Allocated size of the varprefix array.
* expr Parsed expression, if needed.
* stats Time spent in this command.
*/
@ -537,9 +534,7 @@ typedef struct Command
MetaCommand meta;
int argc;
char *argv[MAX_ARGS];
int nqueries;
char **varprefix;
int varprefix_max;
char *varprefix;
PgBenchExpr *expr;
SimpleStats stats;
} Command;
@ -619,7 +614,6 @@ static void doLog(TState *thread, CState *st,
static void processXactStats(TState *thread, CState *st, instr_time *now,
bool skipped, StatsData *agg);
static void pgbench_error(const char *fmt,...) pg_attribute_printf(1, 2);
static void allocate_command_varprefix(Command *cmd, int totalqueries);
static void addScript(ParsedScript script);
static void *threadRun(void *arg);
static void finishCon(CState *st);
@ -2614,8 +2608,6 @@ getMetaCommand(const char *cmd)
mc = META_ELSE;
else if (pg_strcasecmp(cmd, "endif") == 0)
mc = META_ENDIF;
else if (pg_strcasecmp(cmd, "cset") == 0)
mc = META_CSET;
else if (pg_strcasecmp(cmd, "gset") == 0)
mc = META_GSET;
else
@ -2848,24 +2840,30 @@ sendCommand(CState *st, Command *command)
/*
* Process query response from the backend.
*
* If varprefix is not NULL, it's the array of variable prefix names where to
* store the results.
* If varprefix is not NULL, it's the variable name prefix where to store
* the results of the *last* command.
*
* Returns true if everything is A-OK, false if any error occurs.
*/
static bool
readCommandResponse(CState *st, char **varprefix)
readCommandResponse(CState *st, char *varprefix)
{
PGresult *res;
int qrynum = 0;
while ((res = PQgetResult(st->con)) != NULL)
res = PQgetResult(st->con);
while (res != NULL)
{
/* look now at the next result to know whether it is the last */
PGresult *next_res = PQgetResult(st->con);
bool is_last = (next_res == NULL);
switch (PQresultStatus(res))
{
case PGRES_COMMAND_OK: /* non-SELECT commands */
case PGRES_EMPTY_QUERY: /* may be used for testing no-op overhead */
if (varprefix && varprefix[qrynum] != NULL)
if (is_last && varprefix != NULL)
{
fprintf(stderr,
"client %d script %d command %d query %d: expected one row, got %d\n",
@ -2876,7 +2874,7 @@ readCommandResponse(CState *st, char **varprefix)
break;
case PGRES_TUPLES_OK:
if (varprefix && varprefix[qrynum] != NULL)
if (is_last && varprefix != NULL)
{
if (PQntuples(res) != 1)
{
@ -2895,9 +2893,8 @@ readCommandResponse(CState *st, char **varprefix)
char *varname = PQfname(res, fld);
/* allocate varname only if necessary, freed below */
if (*varprefix[qrynum] != '\0')
varname =
psprintf("%s%s", varprefix[qrynum], varname);
if (*varprefix != '\0')
varname = psprintf("%s%s", varprefix, varname);
/* store result as a string */
if (!putVariable(st, "gset", varname,
@ -2914,7 +2911,7 @@ readCommandResponse(CState *st, char **varprefix)
return false;
}
if (*varprefix[qrynum] != '\0')
if (*varprefix != '\0')
pg_free(varname);
}
}
@ -2935,6 +2932,7 @@ readCommandResponse(CState *st, char **varprefix)
PQclear(res);
qrynum++;
res = next_res;
}
if (qrynum == 0)
@ -4248,7 +4246,7 @@ skip_sql_comments(char *sql_command)
* struct.
*/
static Command *
create_sql_command(PQExpBuffer buf, const char *source, int numqueries)
create_sql_command(PQExpBuffer buf, const char *source)
{
Command *my_command;
char *p = skip_sql_comments(buf->data);
@ -4265,9 +4263,7 @@ create_sql_command(PQExpBuffer buf, const char *source, int numqueries)
my_command->meta = META_NONE;
my_command->argc = 0;
memset(my_command->argv, 0, sizeof(my_command->argv));
my_command->nqueries = numqueries;
my_command->varprefix = NULL; /* allocated later, if needed */
my_command->varprefix_max = 0;
my_command->expr = NULL;
initSimpleStats(&my_command->stats);
@ -4284,39 +4280,14 @@ free_command(Command *command)
for (int i = 0; i < command->argc; i++)
pg_free(command->argv[i]);
if (command->varprefix)
{
for (int i = 0; i < command->varprefix_max; i++)
if (command->varprefix[i] &&
command->varprefix[i][0] != '\0') /* see ParseScript */
pg_free(command->varprefix[i]);
pg_free(command->varprefix);
}
/*
* It should also free expr recursively, but this is currently not needed
* as only \{g,c}set commands (which do not have an expression) are freed.
* as only gset commands (which do not have an expression) are freed.
*/
pg_free(command);
}
/*
* append "more" text to current compound command which had been interrupted
* by \cset.
*/
static void
append_sql_command(Command *my_command, char *more, int numqueries)
{
Assert(my_command->type == SQL_COMMAND && my_command->lines.len > 0);
more = skip_sql_comments(more);
if (more == NULL)
return;
/* append command text, embedding a ';' in place of the \cset */
appendPQExpBuffer(&my_command->lines, ";\n%s", more);
my_command->nqueries += numqueries;
}
/*
* Once an SQL command is fully parsed, possibly by accumulating several
* parts, complete other fields of the Command structure.
@ -4350,35 +4321,6 @@ postprocess_sql_command(Command *my_command)
}
}
/*
* Determine the command's varprefix size needed and allocate memory for it
*/
static void
allocate_command_varprefix(Command *cmd, int totalqueries)
{
int new_max;
/* sufficient space already allocated? */
if (totalqueries <= cmd->varprefix_max)
return;
/* determine the new array size */
new_max = Max(cmd->varprefix_max, 2);
while (new_max < totalqueries)
new_max *= 2;
/* enlarge the array, zero-initializing the allocated space */
if (cmd->varprefix == NULL)
cmd->varprefix = pg_malloc0(sizeof(char *) * new_max);
else
{
cmd->varprefix = pg_realloc(cmd->varprefix, sizeof(char *) * new_max);
memset(cmd->varprefix + cmd->varprefix_max, 0,
sizeof(char *) * (new_max - cmd->varprefix_max));
}
cmd->varprefix_max = new_max;
}
/*
* Parse a backslash command; return a Command struct, or NULL if comment
*
@ -4549,7 +4491,7 @@ process_backslash_command(PsqlScanState sstate, const char *source)
syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
"unexpected argument", NULL, -1);
}
else if (my_command->meta == META_CSET || my_command->meta == META_GSET)
else if (my_command->meta == META_GSET)
{
if (my_command->argc > 2)
syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
@ -4637,7 +4579,6 @@ ParseScript(const char *script, const char *desc, int weight)
PQExpBufferData line_buf;
int alloc_num;
int index;
bool saw_cset = false;
int lineno;
int start_offset;
@ -4674,31 +4615,18 @@ ParseScript(const char *script, const char *desc, int weight)
PsqlScanResult sr;
promptStatus_t prompt;
Command *command = NULL;
int semicolons;
resetPQExpBuffer(&line_buf);
lineno = expr_scanner_get_lineno(sstate, start_offset);
sr = psql_scan(sstate, &line_buf, &prompt);
semicolons = psql_scan_get_escaped_semicolons(sstate);
/* If we collected a new SQL command, process that */
command = create_sql_command(&line_buf, desc);
if (saw_cset)
{
/* the previous multi-line command ended with \cset */
append_sql_command(ps.commands[index - 1], line_buf.data,
semicolons + 1);
saw_cset = false;
}
else
{
/* If we collected a new SQL command, process that */
command = create_sql_command(&line_buf, desc, semicolons + 1);
/* store new command */
if (command)
ps.commands[index++] = command;
}
/* store new command */
if (command)
ps.commands[index++] = command;
/* If we reached a backslash, process that */
if (sr == PSCAN_BACKSLASH)
@ -4708,56 +4636,31 @@ ParseScript(const char *script, const char *desc, int weight)
if (command)
{
/*
* If this is gset/cset, merge into the preceding command. (We
* If this is gset, merge into the preceding command. (We
* don't use a command slot in this case).
*/
if (command->meta == META_CSET ||
command->meta == META_GSET)
if (command->meta == META_GSET)
{
int cindex;
Command *cmd;
/*
* If \cset is seen, set flag to leave the command pending
* for the next iteration to process.
*/
saw_cset = command->meta == META_CSET;
if (index == 0)
syntax_error(desc, lineno, NULL, NULL,
"\\gset/cset cannot start a script",
"\\gset must follow a SQL command",
NULL, -1);
cmd = ps.commands[index - 1];
if (cmd->type != SQL_COMMAND)
if (cmd->type != SQL_COMMAND ||
cmd->varprefix != NULL)
syntax_error(desc, lineno, NULL, NULL,
"\\gset/cset must follow a SQL command",
"\\gset must follow a SQL command",
cmd->first_line, -1);
/* this {g,c}set applies to the previous query */
cindex = cmd->nqueries - 1;
/*
* now that we know there's a {g,c}set in this command,
* allocate space for the variable name prefix array.
*/
allocate_command_varprefix(cmd, cmd->nqueries);
/*
* Don't allow the previous command be a gset/cset; that
* would make no sense.
*/
if (cmd->varprefix[cindex] != NULL)
syntax_error(desc, lineno, NULL, NULL,
"\\gset/cset cannot follow one another",
NULL, -1);
/* get variable prefix */
if (command->argc <= 1 || command->argv[1][0] == '\0')
cmd->varprefix[cindex] = ""; /* avoid strdup */
cmd->varprefix = pg_strdup("");
else
cmd->varprefix[cindex] = pg_strdup(command->argv[1]);
cmd->varprefix = pg_strdup(command->argv[1]);
/* cleanup unused command */
free_command(command);

47
src/bin/pgbench/t/001_pgbench_with_server.pl
View File

@ -538,22 +538,18 @@ pgbench(
}
});
# working \gset and \cset
# working \gset
pgbench(
'-t 1', 0,
[ qr{type: .*/001_pgbench_gset_and_cset}, qr{processed: 1/1} ],
[ qr{type: .*/001_pgbench_gset}, qr{processed: 1/1} ],
[ qr{command=3.: int 0\b},
qr{command=5.: int 1\b},
qr{command=6.: int 2\b},
qr{command=8.: int 3\b},
qr{command=9.: int 4\b},
qr{command=10.: int 5\b},
qr{command=12.: int 6\b},
qr{command=13.: int 7\b},
qr{command=14.: int 8\b},
qr{command=16.: int 9\b} ],
'pgbench gset and cset commands',
{ '001_pgbench_gset_and_cset' => q{-- test gset and cset
qr{command=10.: int 4\b},
qr{command=12.: int 5\b} ],
'pgbench gset command',
{ '001_pgbench_gset' => q{-- test gset
-- no columns
SELECT \gset
-- one value
@ -563,21 +559,15 @@ SELECT 0 AS i0 \gset
SELECT 1 AS i1, 2 AS i2 \gset
\set i debug(:i1)
\set i debug(:i2)
-- cset & gset to follow
SELECT :i2 + 1 AS i3, :i2 * :i2 AS i4 \cset
SELECT 5 AS i5 \gset
\set i debug(:i3)
\set i debug(:i4)
\set i debug(:i5)
-- with prefix
SELECT 6 AS i6, 7 AS i7 \cset x_
SELECT 8 AS i8 \gset y_
\set i debug(:x_i6)
\set i debug(:x_i7)
\set i debug(:y_i8)
SELECT 3 AS i3 \gset x_
\set i debug(:x_i3)
-- overwrite existing variable
SELECT 0 AS i9, 9 AS i9 \gset
\set i debug(:i9)
SELECT 0 AS i4, 4 AS i4 \gset
\set i debug(:i4)
-- work on the last SQL command under \;
\; \; SELECT 0 AS i5 \; SELECT 5 AS i5 \; \; \gset
\set i debug(:i5)
} });
# trigger many expression errors
@ -772,20 +762,17 @@ SELECT LEAST(}.join(', ', (':i') x 256).q{)}
[ 'bad boolean', 2,
[qr{malformed variable.*trueXXX}], q{\set b :badtrue or true} ],
# GSET & CSET
# GSET
[ 'gset no row', 2,
[qr{expected one row, got 0\b}], q{SELECT WHERE FALSE \gset} ],
[ 'cset no row', 2,
[qr{expected one row, got 0\b}], q{SELECT WHERE FALSE \cset
SELECT 1 AS i\gset}, 1 ],
[ 'gset alone', 1, [qr{gset/cset cannot start a script}], q{\gset} ],
[ 'gset alone', 1, [qr{gset must follow a SQL command}], q{\gset} ],
[ 'gset no SQL', 1,
[qr{gset/cset must follow a SQL command}], q{\set i +1
[qr{gset must follow a SQL command}], q{\set i +1
\gset} ],
[ 'gset too many arguments', 1,
[qr{too many arguments}], q{SELECT 1 \gset a b} ],
[ 'gset after gset', 1,
[qr{gset/cset cannot follow one another}], q{SELECT 1 AS i \gset
[qr{gset must follow a SQL command}], q{SELECT 1 AS i \gset
\gset} ],
[ 'gset non SELECT', 2,
[qr{expected one row, got 0}],

24
src/fe_utils/psqlscan.l
View File

@ -693,15 +693,8 @@ other .
* substitution. We want these before {self}, also.
*/
"\\"; {
/* Count semicolons in compound commands */
cur_state->escaped_semicolons++;
/* Force a semicolon into the query buffer */
psqlscan_emit(cur_state, yytext + 1, 1);
}
"\\": {
/* Force a colon into the query buffer */
"\\"[;:] {
/* Force a semi-colon or colon into the query buffer */
psqlscan_emit(cur_state, yytext + 1, 1);
}
@ -1072,9 +1065,6 @@ psql_scan(PsqlScanState state,
/* Set current output target */
state->output_buf = query_buf;
/* Reset number of escaped semicolons seen */
state->escaped_semicolons = 0;
/* Set input source */
if (state->buffer_stack != NULL)
yy_switch_to_buffer(state->buffer_stack->buf, state->scanner);
@ -1218,16 +1208,6 @@ psql_scan_reset(PsqlScanState state)
state->dolqstart = NULL;
}
/*
* Return the number of escaped semicolons in the lexed string seen by the
* previous psql_scan call.
*/
int
psql_scan_get_escaped_semicolons(PsqlScanState state)
{
return state->escaped_semicolons;
}
/*
* Reselect this lexer (psqlscan.l) after using another one.
*

2
src/include/fe_utils/psqlscan.h
View File

@ -90,8 +90,6 @@ extern PsqlScanResult psql_scan(PsqlScanState state,
extern void psql_scan_reset(PsqlScanState state);
extern int psql_scan_get_escaped_semicolons(PsqlScanState state);
extern void psql_scan_reselect_sql_lexer(PsqlScanState state);
extern bool psql_scan_in_quote(PsqlScanState state);

1
src/include/fe_utils/psqlscan_int.h
View File

@ -112,7 +112,6 @@ typedef struct PsqlScanStateData
int start_state; /* yylex's starting/finishing state */
int paren_depth; /* depth of nesting in parentheses */
int xcdepth; /* depth of nesting in slash-star comments */
int escaped_semicolons; /* number of embedded (\;) semicolons */
char *dolqstart; /* current $foo$ quote start string */
/*