зеркало из https://github.com/mozilla/gecko-dev.git
Bug 391709, Clean up nsDownloadManager::InitDB schema checking code, r=sdwilsh
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flamingice@sourmilk.net
Родитель
ff240f5bc0
Коммит
ed197ecd00
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@ -195,14 +195,91 @@ nsDownloadManager::InitDB(PRBool *aDoImport)
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*aDoImport = PR_TRUE;
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rv = CreateTable();
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NS_ENSURE_SUCCESS(rv, rv);
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} else {
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// Checking the database schema now
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PRInt32 schemaVersion;
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rv = mDBConn->GetSchemaVersion(&schemaVersion);
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NS_ENSURE_SUCCESS(rv, rv);
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return NS_OK;
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}
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if (0 == schemaVersion) {
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NS_WARNING("Could not get downlaod's database schema version!");
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// Checking the database schema now
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PRInt32 schemaVersion;
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rv = mDBConn->GetSchemaVersion(&schemaVersion);
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NS_ENSURE_SUCCESS(rv, rv);
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// Changing the database? Be sure to do these two things!
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// 1) Increment DM_SCHEMA_VERSION
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// 2) Implement the proper downgrade/upgrade code for the current version
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switch (schemaVersion) {
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// Upgrading
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// Every time you increment the database schema, you need to implement
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// the upgrading code from the previous version to the new one.
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// Also, don't forget to make a unit test to test your upgrading code!
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case 1: // Drop a column (iconURL) from the database (bug 385875)
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{
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// Safely wrap this in a transaction so we don't hose the whole DB
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mozStorageTransaction safeTransaction(mDBConn, PR_TRUE);
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// Create a temporary table that will store the existing records
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"CREATE TEMPORARY TABLE moz_downloads_backup ("
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"id INTEGER PRIMARY KEY, "
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"name TEXT, "
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"source TEXT, "
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"target TEXT, "
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"startTime INTEGER, "
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"endTime INTEGER, "
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"state INTEGER"
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")"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Insert into a temporary table
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"INSERT INTO moz_downloads_backup "
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"SELECT id, name, source, target, startTime, endTime, state "
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"FROM moz_downloads"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Drop the old table
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"DROP TABLE moz_downloads"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Now recreate it with this schema version
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"CREATE TABLE moz_downloads ("
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"id INTEGER PRIMARY KEY, "
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"name TEXT, "
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"source TEXT, "
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"target TEXT, "
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"startTime INTEGER, "
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"endTime INTEGER, "
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"state INTEGER"
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")"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Insert the data back into it
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"INSERT INTO moz_downloads "
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"SELECT id, name, source, target, startTime, endTime, state "
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"FROM moz_downloads_backup"));
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NS_ENSURE_SUCCESS(rv, rv);
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// And drop our temporary table
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"DROP TABLE moz_downloads_backup"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Finally, update the schemaVersion variable and the database schema
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schemaVersion = 2;
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rv = mDBConn->SetSchemaVersion(schemaVersion);
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NS_ENSURE_SUCCESS(rv, rv);
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}
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// Fallthrough to the next upgrade
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case DM_SCHEMA_VERSION:
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break;
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case 0:
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{
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NS_WARNING("Could not get download database's schema version!");
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// The table may still be usable - someone may have just messed with the
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// schema version, so let's just treat this like a downgrade and verify
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@ -210,115 +287,40 @@ nsDownloadManager::InitDB(PRBool *aDoImport)
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// the table anyway.
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rv = mDBConn->SetSchemaVersion(DM_SCHEMA_VERSION);
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NS_ENSURE_SUCCESS(rv, rv);
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// setting it to a large number so we execute a downgrade. This may
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// seem odd, but downgrading checks to see if we have the correct
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// columns in our table. At this point we've established that we have
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// a table, but no schema version, so we want to check this.
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schemaVersion = DM_SCHEMA_VERSION + 1;
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}
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// Fallthrough to downgrade check
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if (schemaVersion != DM_SCHEMA_VERSION) {
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// Changing the database? Be sure to do these two things!
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// 1) Increment DM_SCHEMA_VERSION
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// 2) Implement the proper downgrade/upgrade code for the current version
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// Downgrading
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// If columns have been added to the table, we can still use the ones we
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// understand safely. If columns have been deleted or alterd, we just
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// drop the table and start from scratch. If you change how a column
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// should be interpreted, make sure you also change its name so this
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// check will catch it.
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default:
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{
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nsCOMPtr<mozIStorageStatement> stmt;
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rv = mDBConn->CreateStatement(NS_LITERAL_CSTRING(
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"SELECT id, name, source, target, startTime, endTime, state "
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"FROM moz_downloads"), getter_AddRefs(stmt));
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if (NS_SUCCEEDED(rv))
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break;
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if (schemaVersion > DM_SCHEMA_VERSION) {
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// Downgrading
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// If columns have been added to the table, we can still use the ones we
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// understand safely. If columns have been deleted or alterd, we just
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// drop the table and start from scratch. If you change how a column
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// should be interpreted, make sure you also change its name so this
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// check will catch it.
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// if the statement fails, that means all the columns were not there.
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// First we backup the database
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nsCOMPtr<nsIFile> backup;
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rv = mDBConn->BackupDB(DM_DB_CORRUPT_FILENAME, nsnull,
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getter_AddRefs(backup));
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NS_ENSURE_SUCCESS(rv, rv);
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nsCOMPtr<mozIStorageStatement> stmt;
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rv = mDBConn->CreateStatement(NS_LITERAL_CSTRING(
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"SELECT id, name, source, target, iconURL, startTime, endTime, state "
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"FROM moz_downloads"), getter_AddRefs(stmt));
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if (NS_FAILED(rv)) {
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// if the statement fails, that means all the columns were not there.
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// First we backup the database
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nsCOMPtr<nsIFile> backup;
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rv = mDBConn->BackupDB(DM_DB_CORRUPT_FILENAME, nsnull,
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getter_AddRefs(backup));
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NS_ENSURE_SUCCESS(rv, rv);
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// Then we dump it
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"DROP TABLE moz_downloads"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Then we dump it
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"DROP TABLE moz_downloads"));
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NS_ENSURE_SUCCESS(rv, rv);
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rv = CreateTable();
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NS_ENSURE_SUCCESS(rv, rv);
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}
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} else {
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// Upgrading
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// Every time you increment the database schema, you need to implement
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// the upgrading code from the previous version to the new one.
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// Also, don't forget to make a unit test to test your upgradeing code!
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if (schemaVersion < 2) {
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// This version simple drops a column from the database (iconURL)
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// Safely wrap this in a transaction so we don't hose the whole DB
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mozStorageTransaction safeTransaction(mDBConn, PR_TRUE);
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// Create a temporary table that we'll store the existing records
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"CREATE TEMPORARY TABLE moz_downloads_backup ("
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"id INTEGER PRIMARY KEY, "
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"name TEXT, "
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"source TEXT, "
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"target TEXT, "
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"startTime INTEGER, "
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"endTime INTEGER, "
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"state INTEGER"
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")"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Insert into a temporary table
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"INSERT INTO moz_downloads_backup "
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"SELECT id, name, source, target, startTime, endTime, state "
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"FROM moz_downloads"));
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NS_ENSURE_SUCCESS(rv, rv);
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// drop the old table
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"DROP TABLE moz_downloads"));
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NS_ENSURE_SUCCESS(rv, rv);
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// now recreate it with this schema version
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"CREATE TABLE moz_downloads ("
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"id INTEGER PRIMARY KEY, "
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"name TEXT, "
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"source TEXT, "
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"target TEXT, "
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"startTime INTEGER, "
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"endTime INTEGER, "
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"state INTEGER"
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")"));
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NS_ENSURE_SUCCESS(rv, rv);
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// insert the data back into it
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"INSERT INTO moz_downloads "
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"SELECT id, name, source, target, startTime, endTime, state "
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"FROM moz_downloads_backup"));
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NS_ENSURE_SUCCESS(rv, rv);
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// and drop our temporary table
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rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
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"DROP TABLE moz_downloads_backup"));
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NS_ENSURE_SUCCESS(rv, rv);
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// Finally, update the schemaVersion variable and the database schema
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schemaVersion = 2;
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rv = mDBConn->SetSchemaVersion(schemaVersion);
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NS_ENSURE_SUCCESS(rv, rv);
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} // End of schema #2 upgrade code
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} // End of upgrading
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rv = CreateTable();
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NS_ENSURE_SUCCESS(rv, rv);
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}
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break;
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}
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return NS_OK;
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