Add parameters to select metadata sample columns

2018-05-28 16:08:31 +02:00
parent f7c80a0101
commit 4bb8914d9a
2 changed files with 46 additions and 9 deletions
@@ -88,17 +88,27 @@ 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;
+    }
+    return columns.map(name => `"${name}"`).join(', ');
+}
+
+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 +120,9 @@ 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}
    `;
 }