fabc2ba6a2
Instead of getting batches of unused primary key ids, even if they're lower than other ids, which for some reason seemed like a good idea in 2008, just do a `MAX()` on the table at startup and return the next available id on each call to `Zotero.ID.get()`. This is much simpler, and not reusing ids allows them to be used as a chronological sort field. While SQLite's `SELECT last_insert_rowid()` could return auto-increment values, it's unsafe with async DB access, since a second `INSERT` can come in before the first `last_insert_rowid()` is called. This is true even in a transaction unless a function that calls it is never called in parallel (e.g., with `Zotero.Promise.all()`, which can be faster than sequential `yield`s). Note that the next id is always initialized as MAX() + 1, so if an object is added and then deleted, after a restart the same id will be given. (This is equivalent to (though unrelated to) SQLite's `INTEGER PRIMARY KEY` behavior, as opposed to its `INTEGER PRIMARY KEY AUTOINCREMENT` behavior.) Closes #993, Feed items out of order
96 lines
2.2 KiB
JavaScript
96 lines
2.2 KiB
JavaScript
/*
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***** BEGIN LICENSE BLOCK *****
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Copyright © 2016 Center for History and New Media
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George Mason University, Fairfax, Virginia, USA
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https://www.zotero.org
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This file is part of Zotero.
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Zotero is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Zotero is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with Zotero. If not, see <http://www.gnu.org/licenses/>.
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***** END LICENSE BLOCK *****
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*/
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Zotero.ID_Tracker = function () {
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var _tables = [
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'collections',
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'creators',
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'customFields',
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'customItemTypes',
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'itemDataValues',
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'items',
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'libraries',
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'proxies',
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'savedSearches',
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'tags'
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];
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var _nextIDs = {};
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this.init = Zotero.Promise.coroutine(function* () {
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for (let table of _tables) {
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_nextIDs[table] = yield _getNext(table);
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}
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});
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/**
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* Gets an unused primary key id for a DB table
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*/
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this.get = function (table) {
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if (!_nextIDs[table]) {
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throw new Error("IDs not loaded for table '" + table + "'");
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}
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return ++_nextIDs[table];
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};
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function _getTableColumn(table) {
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switch (table) {
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case 'libraries':
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return 'libraryID';
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case 'itemDataValues':
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return 'valueID';
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case 'savedSearches':
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return 'savedSearchID';
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case 'creatorData':
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return 'creatorDataID';
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case 'proxies':
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return 'proxyID';
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default:
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return table.substr(0, table.length - 1) + 'ID';
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}
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}
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/**
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* Get MAX(id) + 1 from table
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*
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* @return {Promise<Integer>}
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*/
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function _getNext(table) {
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var sql = 'SELECT COALESCE(MAX(' + _getTableColumn(table) + ') + 1, 1) FROM ' + table;
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return Zotero.DB.valueQueryAsync(sql);
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};
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}
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Zotero.ID = new Zotero.ID_Tracker;
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