ClickHouse/dbms/programs/client/Suggest.h

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#pragma once
#include "ConnectionParameters.h"
#include <string>
#include <sstream>
#include <string.h>
#include <vector>
#include <algorithm>
#include <ext/singleton.h>
#include <common/readline_use.h>
#include <Common/typeid_cast.h>
#include <Columns/ColumnString.h>
#include <Client/Connection.h>
namespace DB
{
namespace ErrorCodes
{
extern const int UNKNOWN_PACKET_FROM_SERVER;
}
class Suggest : public ext::singleton<Suggest>
{
private:
/// The vector will be filled with completion words from the server and sorted.
using Words = std::vector<std::string>;
/// Keywords may be not up to date with ClickHouse parser.
Words words
{
"CREATE", "DATABASE", "IF", "NOT", "EXISTS", "TEMPORARY", "TABLE", "ON", "CLUSTER", "DEFAULT", "MATERIALIZED", "ALIAS", "ENGINE",
"AS", "VIEW", "POPULATE", "SETTINGS", "ATTACH", "DETACH", "DROP", "RENAME", "TO", "ALTER", "ADD", "MODIFY", "CLEAR", "COLUMN", "AFTER",
"COPY", "PROJECT", "PRIMARY", "KEY", "CHECK", "PARTITION", "PART", "FREEZE", "FETCH", "FROM", "SHOW", "INTO", "OUTFILE", "FORMAT", "TABLES",
"DATABASES", "LIKE", "PROCESSLIST", "CASE", "WHEN", "THEN", "ELSE", "END", "DESCRIBE", "DESC", "USE", "SET", "OPTIMIZE", "FINAL", "DEDUPLICATE",
"INSERT", "VALUES", "SELECT", "DISTINCT", "SAMPLE", "ARRAY", "JOIN", "GLOBAL", "LOCAL", "ANY", "ALL", "INNER", "LEFT", "RIGHT", "FULL", "OUTER",
"CROSS", "USING", "PREWHERE", "WHERE", "GROUP", "BY", "WITH", "TOTALS", "HAVING", "ORDER", "COLLATE", "LIMIT", "UNION", "AND", "OR", "ASC", "IN",
"KILL", "QUERY", "SYNC", "ASYNC", "TEST", "BETWEEN"
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};
/// Words are fetched asynchonously.
std::thread loading_thread;
std::atomic<bool> ready{false};
/// Points to current word to suggest.
Words::const_iterator pos;
/// Points after the last possible match.
Words::const_iterator end;
/// Set iterators to the matched range of words if any.
void findRange(const char * prefix, size_t prefix_length)
{
std::string prefix_str(prefix);
std::tie(pos, end) = std::equal_range(words.begin(), words.end(), prefix_str,
[prefix_length](const std::string & s, const std::string & prefix_searched) { return strncmp(s.c_str(), prefix_searched.c_str(), prefix_length) < 0; });
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}
/// Iterates through matched range.
char * nextMatch()
{
if (pos >= end)
return nullptr;
/// readline will free memory by itself.
char * word = strdup(pos->c_str());
++pos;
return word;
}
void loadImpl(Connection & connection, size_t suggestion_limit)
{
std::stringstream query;
query << "SELECT DISTINCT arrayJoin(extractAll(name, '[\\\\w_]{2,}')) AS res FROM ("
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"SELECT name FROM system.functions"
" UNION ALL "
"SELECT name FROM system.table_engines"
" UNION ALL "
"SELECT name FROM system.formats"
" UNION ALL "
"SELECT name FROM system.table_functions"
" UNION ALL "
"SELECT name FROM system.data_type_families"
" UNION ALL "
"SELECT name FROM system.settings"
" UNION ALL "
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"SELECT concat(func.name, comb.name) FROM system.functions AS func CROSS JOIN system.aggregate_function_combinators AS comb WHERE is_aggregate";
/// The user may disable loading of databases, tables, columns by setting suggestion_limit to zero.
if (suggestion_limit > 0)
{
String limit_str = toString(suggestion_limit);
query <<
" UNION ALL "
"SELECT name FROM system.databases LIMIT " << limit_str
<< " UNION ALL "
"SELECT DISTINCT name FROM system.tables LIMIT " << limit_str
<< " UNION ALL "
"SELECT DISTINCT name FROM system.columns LIMIT " << limit_str;
}
query << ") WHERE notEmpty(res)";
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fetch(connection, query.str());
}
void fetch(Connection & connection, const std::string & query)
{
connection.sendQuery(query);
while (true)
{
Connection::Packet packet = connection.receivePacket();
switch (packet.type)
{
case Protocol::Server::Data:
fillWordsFromBlock(packet.block);
continue;
case Protocol::Server::Progress:
continue;
case Protocol::Server::ProfileInfo:
continue;
case Protocol::Server::Totals:
continue;
case Protocol::Server::Extremes:
continue;
case Protocol::Server::Log:
continue;
case Protocol::Server::Exception:
packet.exception->rethrow();
return;
case Protocol::Server::EndOfStream:
return;
default:
throw Exception("Unknown packet from server", ErrorCodes::UNKNOWN_PACKET_FROM_SERVER);
}
}
}
void fillWordsFromBlock(const Block & block)
{
if (!block)
return;
if (block.columns() != 1)
throw Exception("Wrong number of columns received for query to read words for suggestion", ErrorCodes::LOGICAL_ERROR);
const ColumnString & column = typeid_cast<const ColumnString &>(*block.getByPosition(0).column);
size_t rows = block.rows();
for (size_t i = 0; i < rows; ++i)
words.emplace_back(column.getDataAt(i).toString());
}
public:
/// More old server versions cannot execute the query above.
static constexpr int MIN_SERVER_REVISION = 54406;
void load(const ConnectionParameters & connection_parameters, size_t suggestion_limit)
{
loading_thread = std::thread([connection_parameters, suggestion_limit, this]
{
try
{
Connection connection(
connection_parameters.host,
connection_parameters.port,
connection_parameters.default_database,
connection_parameters.user,
connection_parameters.password,
connection_parameters.timeouts,
"client",
connection_parameters.compression,
connection_parameters.security);
loadImpl(connection, suggestion_limit);
}
catch (...)
{
std::cerr << "Cannot load data for command line suggestions: " << getCurrentExceptionMessage(false, true) << "\n";
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}
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/// Note that keyword suggestions are available even if we cannot load data from server.
std::sort(words.begin(), words.end());
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ready = true;
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});
}
void finalize()
{
if (loading_thread.joinable())
loading_thread.join();
}
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/// A function for readline.
static char * generator(const char * text, int state)
{
Suggest & suggest = Suggest::instance();
if (!suggest.ready)
return nullptr;
if (state == 0)
suggest.findRange(text, strlen(text));
/// Do not append whitespace after word. For unknown reason, rl_completion_append_character = '\0' does not work.
rl_completion_suppress_append = 1;
return suggest.nextMatch();
}
~Suggest()
{
finalize();
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}
};
}