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support older PostGreSQL versions (#4999)

* support older PostGreSQL versions
* documentation accuracy

* improve performance by affecting less rows in UPDATE queries
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zeuner authored and nerzhul committed Jan 9, 2017
1 parent 73fdb63 commit 11df7e886a674e280e3ec6f895c11fc1e70eb7b3
Showing with 26 additions and 7 deletions.
  1. +1 −1 README.txt
  2. +25 −6 src/database-postgresql.cpp
@@ -178,7 +178,7 @@ ENABLE_FREETYPE - Build with FreeType2; Allows using TTF fonts
ENABLE_GETTEXT - Build with Gettext; Allows using translations
ENABLE_GLES - Search for Open GLES headers & libraries and use them
ENABLE_LEVELDB - Build with LevelDB; Enables use of LevelDB map backend
ENABLE_POSTGRESQL - Build with libpq; Enables use of PostgreSQL map backend (PostgreSQL 9.5 or greater required)
ENABLE_POSTGRESQL - Build with libpq; Enables use of PostgreSQL map backend (PostgreSQL 9.5 or greater recommended)
ENABLE_REDIS - Build with libhiredis; Enables use of Redis map backend
ENABLE_SPATIAL - Build with LibSpatial; Speeds up AreaStores
ENABLE_SOUND - Build with OpenAL, libogg & libvorbis; in-game Sounds
@@ -80,12 +80,12 @@ void Database_PostgreSQL::connectToDatabase()

/*
* We are using UPSERT feature from PostgreSQL 9.5
* to have the better performance,
* set the minimum version to 90500
* to have the better performance where possible.
*/
if (m_pgversion < 90500) {
throw DatabaseException("PostgreSQL database error: "
"Server version 9.5 or greater required.");
warningstream << "Your PostgreSQL server lacks UPSERT "
<< "support. Use version 9.5 or better if possible."
<< std::endl;
}

infostream << "PostgreSQL Database: Version " << m_pgversion
@@ -125,11 +125,25 @@ void Database_PostgreSQL::initStatements()
"WHERE posX = $1::int4 AND posY = $2::int4 AND "
"posZ = $3::int4");

prepareStatement("write_block",
if (m_pgversion < 90500) {
prepareStatement("write_block_insert",
"INSERT INTO blocks (posX, posY, posZ, data) SELECT "
"$1::int4, $2::int4, $3::int4, $4::bytea "
"WHERE NOT EXISTS (SELECT true FROM blocks "
"WHERE posX = $1::int4 AND posY = $2::int4 AND "
"posZ = $3::int4)");

prepareStatement("write_block_update",
"UPDATE blocks SET data = $4::bytea "
"WHERE posX = $1::int4 AND posY = $2::int4 AND "
"posZ = $3::int4");
} else {
prepareStatement("write_block",
"INSERT INTO blocks (posX, posY, posZ, data) VALUES "
"($1::int4, $2::int4, $3::int4, $4::bytea) "
"ON CONFLICT ON CONSTRAINT blocks_pkey DO "
"UPDATE SET data = $4::bytea");
}

prepareStatement("delete_block", "DELETE FROM blocks WHERE "
"posX = $1::int4 AND posY = $2::int4 AND posZ = $3::int4");
@@ -218,7 +232,12 @@ bool Database_PostgreSQL::saveBlock(const v3s16 &pos,
};
const int argFmt[] = { 1, 1, 1, 1 };

execPrepared("write_block", ARRLEN(args), args, argLen, argFmt);
if (m_pgversion < 90500) {
execPrepared("write_block_update", ARRLEN(args), args, argLen, argFmt);
execPrepared("write_block_insert", ARRLEN(args), args, argLen, argFmt);
} else {
execPrepared("write_block", ARRLEN(args), args, argLen, argFmt);
}
return true;
}

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