diff --git a/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js b/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js index 3a7a3358..d8320334 100644 --- a/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js +++ b/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js @@ -146,13 +146,20 @@ function mergeColumns(results) { } } +const SAMPLE_SEED = 0.5; +const DEFAULT_SAMPLE_ROWS = 100; + function _sample(ctx, numRows) { if (ctx.metaOptions.sample) { - const sampleProb = Math.min(ctx.metaOptions.sample / numRows, 1); + const sampleProb = Math.min(ctx.metaOptions.sample.num_rows / numRows, 1); // We'll use a safety limit just in case numRows is a bad estimate - const limit = Math.ceil(ctx.metaOptions.sample * 1.5); - return queryPromise(ctx.dbConnection, _getSQL(ctx, sql => queryUtils.getQuerySample(sql, sampleProb, limit))) - .then(res => ({ sample: res.rows })); + const requestedRows = ctx.metaOptions.sample.num_rows || DEFAULT_SAMPLE_ROWS; + const limit = Math.ceil(requestedRows * 1.5); + let columns = ctx.metaOptions.sample.include_columns; + return queryPromise(ctx.dbConnection, _getSQL( + ctx, + sql => queryUtils.getQuerySample(sql, sampleProb, limit, SAMPLE_SEED, columns) + )).then(res => ({ sample: res.rows })); } return Promise.resolve(); } @@ -265,6 +272,8 @@ function (layer, dbConnection, callback) { // (if metaOptions.geometryType) from it. // TODO: compute _sample with _featureCount when available + // TODO: add support for sample.exclude option by, in that case, forcing the columns query and + // passing the results to the sample query function. Promise.all([ _estimatedFeatureCount(ctx).then( diff --git a/lib/cartodb/utils/query-utils.js b/lib/cartodb/utils/query-utils.js index 22d99eef..867db0cd 100644 --- a/lib/cartodb/utils/query-utils.js +++ b/lib/cartodb/utils/query-utils.js @@ -88,17 +88,30 @@ module.exports.getQueryTopCategories = function(query, column, topN, includeNull `; }; -module.exports.getQuerySample = function(query, sampleProb, limit = null, randomSeed = 0.5) { +function columnSelector(columns) { + if (!columns) { + return '*'; + } + if (typeof columns === 'string') { + return columns; + } + if (Array.isArray(columns)) { + return columns.map(name => `"${name}"`).join(', '); + } + throw new TypeError(`Bad argument type for columns: ${typeof columns}`); +} + +module.exports.getQuerySample = function(query, sampleProb, limit = null, randomSeed = 0.5, columns = null) { const singleTable = simpleQueryTable(query); if (singleTable) { - return getTableSample(singleTable.table, singleTable.columns, sampleProb, limit, randomSeed); + return getTableSample(singleTable.table, columns || singleTable.columns, sampleProb, limit, randomSeed); } const limitClause = limit ? `LIMIT ${limit}` : ''; return ` WITH __cdb_rndseed AS ( SELECT setseed(${randomSeed}) ) - SELECT * + SELECT ${columnSelector(columns)} FROM (${query}) AS __cdb_query WHERE random() < ${sampleProb} ${limitClause} @@ -110,7 +123,9 @@ function getTableSample(table, columns, sampleProb, limit = null, randomSeed = 0 sampleProb *= 100; randomSeed *= Math.pow(2, 31) -1; return ` - SELECT ${columns} FROM ${table} TABLESAMPLE BERNOULLI (${sampleProb}) REPEATABLE (${randomSeed}) ${limitClause} + SELECT ${columnSelector(columns)} + FROM ${table} + TABLESAMPLE BERNOULLI (${sampleProb}) REPEATABLE (${randomSeed}) ${limitClause} `; } diff --git a/test/acceptance/stats/mapnik_stats_layergroup.js b/test/acceptance/stats/mapnik_stats_layergroup.js index 46c4368a..4e8413ae 100644 --- a/test/acceptance/stats/mapnik_stats_layergroup.js +++ b/test/acceptance/stats/mapnik_stats_layergroup.js @@ -513,7 +513,7 @@ describe('Create mapnik layergroup', function() { version: '1.4.0', layers: [ layerWithMetadata(mapnikLayer4, { - sample: 3 + sample: { num_rows: 3 } }) ] }); @@ -529,6 +529,31 @@ describe('Create mapnik layergroup', function() { }); }); + it('can specify sample columns', function(done) { + var testClient = new TestClient({ + version: '1.4.0', + layers: [ + layerWithMetadata(mapnikLayer4, { + sample: { + num_rows: 3, + include_columns: [ 'cartodb_id', 'address', 'the_geom' ] + } + }) + ] + }); + + testClient.getLayergroup(function(err, layergroup) { + assert.ifError(err); + assert.equal(layergroup.metadata.layers[0].id, mapnikBasicLayerId(0)); + assert.equal(layergroup.metadata.layers[0].meta.stats.estimatedFeatureCount, 5); + assert(layergroup.metadata.layers[0].meta.stats.sample.length > 0); + const expectedCols = [ 'cartodb_id', 'address', 'the_geom' ].sort(); + assert.deepEqual(Object.keys(layergroup.metadata.layers[0].meta.stats.sample[0]).sort(), expectedCols); + testClient.drain(done); + }); + }); + + it('should only provide requested optional metadata', function(done) { var testClient = new TestClient({ version: '1.4.0',