102 lines
3.2 KiB
JavaScript
102 lines
3.2 KiB
JavaScript
'use strict';
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var dot = require('dot');
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dot.templateSettings.strip = false;
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function createTemplate(method) {
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return dot.template([
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'SELECT',
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method,
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'FROM ({{=it._sql}}) _table_sql WHERE {{=it._column}} IS NOT NULL'
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].join('\n'));
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}
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var methods = {
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quantiles: 'CDB_QuantileBins(array_agg(distinct({{=it._column}}::numeric)), {{=it._buckets}}) as quantiles',
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equal: 'CDB_EqualIntervalBins(array_agg({{=it._column}}::numeric), {{=it._buckets}}) as equal',
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jenks: 'CDB_JenksBins(array_agg(distinct({{=it._column}}::numeric)), {{=it._buckets}}) as jenks',
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headtails: 'CDB_HeadsTailsBins(array_agg(distinct({{=it._column}}::numeric)), {{=it._buckets}}) as headtails'
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};
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var methodTemplates = Object.keys(methods).reduce(function(methodTemplates, methodName) {
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methodTemplates[methodName] = createTemplate(methods[methodName]);
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return methodTemplates;
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}, {});
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methodTemplates.category = dot.template([
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'WITH',
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'categories AS (',
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' SELECT {{=it._column}} AS category, count(1) AS value, row_number() OVER (ORDER BY count(1) desc) as rank',
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' FROM ({{=it._sql}}) _cdb_aggregation_all',
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' GROUP BY {{=it._column}}',
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' ORDER BY 2 DESC',
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'),',
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'agg_categories AS (',
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' SELECT \'__other\' category',
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' FROM categories',
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' WHERE rank >= {{=it._buckets}}',
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' GROUP BY 1',
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' UNION ALL',
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' SELECT CAST(category AS text)',
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' FROM categories',
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' WHERE rank < {{=it._buckets}}',
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')',
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'SELECT array_agg(category) AS category FROM agg_categories'
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].join('\n'));
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var STRATEGY = {
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SPLIT: 'split',
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EXACT: 'exact'
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};
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var method2strategy = {
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headtails: STRATEGY.SPLIT,
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category: STRATEGY.EXACT
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};
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function PostgresDatasource (psql, query) {
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this.psql = psql;
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this.query = query;
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}
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PostgresDatasource.prototype.getName = function () {
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return 'PostgresDatasource';
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};
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PostgresDatasource.prototype.getRamp = function (column, buckets, method, callback) {
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if (method && !methodTemplates.hasOwnProperty(method)) {
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return callback(new Error(
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'Invalid method "' + method + '", valid methods: [' + Object.keys(methodTemplates).join(',') + ']'
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));
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}
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var methodName = method || 'quantiles';
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var template = methodTemplates[methodName];
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var query = template({ _column: column, _sql: this.query, _buckets: buckets });
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this.psql.query(query, function (err, resultSet) {
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if (err) {
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return callback(err);
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}
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resultSet = resultSet || {};
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var result = resultSet.rows || [];
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var strategy = method2strategy[methodName];
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var ramp = result[0][methodName] || [];
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// Skip null values from ramp
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// Generated turbo-carto won't be correct, but better to keep it working than failing
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// TODO fix cartodb-postgres extension quantification functions
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ramp = ramp.filter(function(value) { return value !== null; });
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if (strategy !== STRATEGY.EXACT) {
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ramp = ramp.sort(function(a, b) {
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return a - b;
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});
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}
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return callback(null, { ramp: ramp, strategy: strategy });
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}, true); // use read-only transaction
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};
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module.exports = PostgresDatasource;
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