PostGIS+PGraster: pass exact floating-point numbers in SQL queries

plugins/input/pgcommon/sql_utils.hpp

@@ -0,0 +1,103 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2019 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ *****************************************************************************/
+
+#ifndef MAPNIK_PLUGINS_INPUT_PGCOMMON_SQL_UTILS_HPP
+#define MAPNIK_PLUGINS_INPUT_PGCOMMON_SQL_UTILS_HPP
+
+// mapnik
+#include <mapnik/geometry/box2d.hpp>
+
+// stl
+#include <algorithm>
+#include <cstdio>
+#include <ostream>
+
+namespace mapnik { namespace pgcommon {
+
+
+// sql_float4
+
+struct sql_float4
+{
+ float value;
+};
+
+inline sql_float4 sql_float(float value)
+{
+ return {value};
+}
+
+inline std::ostream & operator << (std::ostream & os, sql_float4 sf)
+{
+ char const fmt[] = "float4 '%a'";
+ char buf[sizeof(fmt) + 25];
+ int len = std::snprintf(buf, sizeof(buf), fmt, sf.value);
+ return os.write(buf, std::min(len, int(sizeof(buf)) - 1));
+}
+
+
+// sql_float8
+
+struct sql_float8
+{
+ double value;
+};
+
+inline sql_float8 sql_float(double value)
+{
+ return {value};
+}
+
+inline std::ostream & operator << (std::ostream & os, sql_float8 sf)
+{
+ char const fmt[] = "float8 '%a'";
+ char buf[sizeof(fmt) + 25];
+ int len = std::snprintf(buf, sizeof(buf), fmt, sf.value);
+ return os.write(buf, std::min(len, int(sizeof(buf)) - 1));
+}
+
+
+// sql_bbox
+
+struct sql_bbox : box2d<double>
+{
+ int srid_;
+
+ sql_bbox(box2d<double> const& box, int srid)
+ : box2d<double>(box), srid_(srid) {}
+};
+
+inline std::ostream & operator << (std::ostream & os, sql_bbox const& box)
+{
+ char const fmt[] = "ST_MakeEnvelope(float8 '%a', float8 '%a', "
+ "float8 '%a', float8 '%a', %d)";
+ char buf[sizeof(fmt) + 4 * 25 + sizeof(int[3])];
+ int len = std::snprintf(buf, sizeof(buf), fmt,
+ box.minx(), box.miny(), box.maxx(), box.maxy(),
+ std::max(box.srid_, 0));
+ return os.write(buf, std::min(len, int(sizeof(buf)) - 1));
+}
+
+
+}} // namespace mapnik::pgcommon
+
+#endif // MAPNIK_PLUGINS_INPUT_PGCOMMON_SQL_UTILS_HPP

plugins/input/pgraster/pgraster_datasource.cpp

@@ -24,6 +24,7 @@
  *
  *****************************************************************************/
 
+#include "../pgcommon/sql_utils.hpp"
 #include "../postgis/connection_manager.hpp"
 #include "../postgis/asyncresultset.hpp"
 #include "pgraster_datasource.hpp"
@@ -58,6 +59,8 @@ const std::string pgraster_datasource::SPATIAL_REF_SYS = "spatial_ref_system";
 
 using std::shared_ptr;
 using mapnik::attribute_descriptor;
+using mapnik::pgcommon::sql_bbox;
+using mapnik::pgcommon::sql_float;
 using mapnik::sql_utils::identifier;
 using mapnik::sql_utils::literal;
 using mapnik::value_integer;
@@ -589,17 +592,6 @@ layer_descriptor pgraster_datasource::get_descriptor() const
  return desc_;
 }
 
-std::string pgraster_datasource::sql_bbox(box2d<double> const& env) const
-{
- std::ostringstream b;
- b.precision(16);
- b << "ST_MakeEnvelope(";
- b << env.minx() << "," << env.miny() << ",";
- b << env.maxx() << "," << env.maxy() << ",";
- b << std::max(srid_, 0) << ")";
- return b.str();
-}
-
 std::string pgraster_datasource::populate_tokens(std::string const& sql) const
 {
  return populate_tokens(sql, FLT_MAX,
@@ -620,9 +612,6 @@ std::string pgraster_datasource::populate_tokens(std::string const& sql,
  char const* start = sql.data();
  char const* end = start + sql.size();
 
- populated_sql.precision(16);
- populated_sql << std::showpoint;
-
  while (std::regex_search(start, end, m, re_tokens_))
  {
  populated_sql.write(start, m[0].first - start);
@@ -645,20 +634,20 @@ std::string pgraster_datasource::populate_tokens(std::string const& sql,
  }
  else if (boost::algorithm::equals(m1, "bbox"))
  {
- populated_sql << sql_bbox(env);
+ populated_sql << sql_bbox(env, srid_);
  intersect = false;
  }
  else if (boost::algorithm::equals(m1, "pixel_height"))
  {
- populated_sql << pixel_height;
+ populated_sql << sql_float(pixel_height);
  }
  else if (boost::algorithm::equals(m1, "pixel_width"))
  {
- populated_sql << pixel_width;
+ populated_sql << sql_float(pixel_width);
  }
  else if (boost::algorithm::equals(m1, "scale_denominator"))
  {
- populated_sql << scale_denom;
+ populated_sql << sql_float(scale_denom);
  }
  else
  {
@@ -674,7 +663,7 @@ std::string pgraster_datasource::populate_tokens(std::string const& sql,
  {
  populated_sql << " WHERE ST_Intersects("
  << identifier(geometryColumn_) << ", "
- << sql_bbox(env) << ")";
+ << sql_bbox(env, srid_) << ")";
  }
  else if (intersect_max_scale_ > 0 && (scale_denom >= intersect_max_scale_))
  {
@@ -684,7 +673,7 @@ std::string pgraster_datasource::populate_tokens(std::string const& sql,
  {
  populated_sql << " WHERE "
  << identifier(geometryColumn_) << " && "
- << sql_bbox(env);
+ << sql_bbox(env, srid_);
  }
  }
 
@@ -889,7 +878,7 @@ featureset_ptr pgraster_datasource::features_with_context(query const& q,process
  s << identifier(col);
 
  if (clip_rasters_) {
- s << ", ST_Expand(" << sql_bbox(box)
+ s << ", ST_Expand(" << sql_bbox(box, srid_)
  << ", greatest(abs(ST_ScaleX("
  << identifier(col) << ")), abs(ST_ScaleY("
  << identifier(col) << ")))))";
@@ -898,9 +887,9 @@ featureset_ptr pgraster_datasource::features_with_context(query const& q,process
  if (prescale_rasters_) {
  const double scale = std::min(px_gw, px_gh);
  s << ", least(1.0, abs(ST_ScaleX(" << identifier(col)
- << "))::float8/" << scale
+ << "))::float8/" << sql_float(scale)
  << "), least(1.0, abs(ST_ScaleY(" << identifier(col)
- << "))::float8/" << scale << "))";
+ << "))::float8/" << sql_float(scale) << "))";
  // TODO: if band_ is given, we'll interpret as indexed so
  // the rescaling must NOT ruin it (use algorithm mode!)
  }

plugins/input/pgraster/pgraster_datasource.hpp

@@ -90,7 +90,6 @@ class pgraster_datasource : public datasource
  layer_descriptor get_descriptor() const;
 
 private:
- std::string sql_bbox(box2d<double> const& env) const;
  std::string populate_tokens(std::string const& sql, double scale_denom,
  box2d<double> const& env,
  double pixel_width, double pixel_height,

plugins/input/postgis/postgis_datasource.cpp

@@ -20,12 +20,12 @@
  *
  *****************************************************************************/
 
+#include "../pgcommon/sql_utils.hpp"
 #include "connection_manager.hpp"
 #include "postgis_datasource.hpp"
 #include "postgis_featureset.hpp"
 #include "asyncresultset.hpp"
 
-
 // mapnik
 #include <mapnik/debug.hpp>
 #include <mapnik/global.hpp>
@@ -55,6 +55,8 @@ const std::string postgis_datasource::SPATIAL_REF_SYS = "spatial_ref_system";
 
 using std::shared_ptr;
 using mapnik::attribute_descriptor;
+using mapnik::pgcommon::sql_bbox;
+using mapnik::pgcommon::sql_float;
 using mapnik::sql_utils::identifier;
 using mapnik::sql_utils::literal;
 
@@ -499,17 +501,6 @@ layer_descriptor postgis_datasource::get_descriptor() const
  return desc_;
 }
 
-std::string postgis_datasource::sql_bbox(box2d<double> const& env) const
-{
- std::ostringstream b;
- b.precision(16);
- b << "ST_MakeEnvelope(";
- b << env.minx() << "," << env.miny() << ",";
- b << env.maxx() << "," << env.maxy() << ",";
- b << std::max(srid_, 0) << ")";
- return b.str();
-}
-
 std::string postgis_datasource::populate_tokens(std::string const& sql) const
 {
  return populate_tokens(sql, FLT_MAX,
@@ -531,9 +522,6 @@ std::string postgis_datasource::populate_tokens(
  char const* start = sql.data();
  char const* end = start + sql.size();
 
- populated_sql.precision(16);
- populated_sql << std::showpoint;
-
  while (std::regex_search(start, end, m, re_tokens_))
  {
  populated_sql.write(start, m[0].first - start);
@@ -556,20 +544,20 @@ std::string postgis_datasource::populate_tokens(
  }
  else if (boost::algorithm::equals(m1, "bbox"))
  {
- populated_sql << sql_bbox(env);
+ populated_sql << sql_bbox(env, srid_);
  intersect = false;
  }
  else if (boost::algorithm::equals(m1, "pixel_height"))
  {
- populated_sql << pixel_height;
+ populated_sql << sql_float(pixel_height);
  }
  else if (boost::algorithm::equals(m1, "pixel_width"))
  {
- populated_sql << pixel_width;
+ populated_sql << sql_float(pixel_width);
  }
  else if (boost::algorithm::equals(m1, "scale_denominator"))
  {
- populated_sql << scale_denom;
+ populated_sql << sql_float(scale_denom);
  }
  else
  {
@@ -585,7 +573,7 @@ std::string postgis_datasource::populate_tokens(
  {
  populated_sql << " WHERE ST_Intersects("
  << identifier(geometryColumn_) << ", "
- << sql_bbox(env) << ")";
+ << sql_bbox(env, srid_) << ")";
  }
  else if (intersect_max_scale_ > 0 && (scale_denom >= intersect_max_scale_))
  {
@@ -595,7 +583,7 @@ std::string postgis_datasource::populate_tokens(
  {
  populated_sql << " WHERE "
  << identifier(geometryColumn_) << " && "
- << sql_bbox(env);
+ << sql_bbox(env, srid_);
  }
  }
 
@@ -785,13 +773,13 @@ featureset_ptr postgis_datasource::features_with_context(query const& q,processo
  // ! ST_ClipByBox2D()
  if (simplify_clip_resolution_ > 0.0 && simplify_clip_resolution_ > px_sz)
  {
- s << "," << sql_bbox(box) << ")";
+ s << "," << sql_bbox(box, srid_) << ")";
  }
 
  // ! ST_RemoveRepeatedPoints()
- s << "," << twkb_tolerance << ")";
+ s << "," << sql_float(twkb_tolerance) << ")";
  // ! ST_Simplify(), with parameter to keep collapsed geometries
- s << "," << twkb_tolerance << ",true)";
+ s << "," << sql_float(twkb_tolerance) << ",true)";
  // ! ST_TWKB()
  s << "," << twkb_rounding << ") AS geom";
  }
@@ -818,20 +806,20 @@ featureset_ptr postgis_datasource::features_with_context(query const& q,processo
  if (simplify_geometries_ && simplify_snap_ratio_ > 0.0)
  {
  const double tolerance = px_sz * simplify_snap_ratio_;
- s << "," << tolerance << ")";
+ s << "," << sql_float(tolerance) << ")";
  }
 
  // ! ST_ClipByBox2D()
  if (simplify_clip_resolution_ > 0.0 && simplify_clip_resolution_ > px_sz)
  {
- s << "," << sql_bbox(box) << ")";
+ s << "," << sql_bbox(box, srid_) << ")";
  }
 
  // ! ST_Simplify()
  if (simplify_geometries_)
  {
  const double tolerance = px_sz * simplify_dp_ratio_;
- s << ", " << tolerance;
+ s << ", " << sql_float(tolerance);
  // Add parameter to ST_Simplify to keep collapsed geometries
  if (simplify_dp_preserve_)
  {

plugins/input/postgis/postgis_datasource.hpp

@@ -78,7 +78,6 @@ class postgis_datasource : public datasource
  layer_descriptor get_descriptor() const;
 
 private:
- std::string sql_bbox(box2d<double> const& env) const;
  std::string populate_tokens(std::string const& sql,
  double scale_denom,
  box2d<double> const& env,

test/unit/datasource/postgis.cpp

@@ -178,6 +178,18 @@ TEST_CASE("postgis") {
  auto ds = mapnik::datasource_cache::instance().create(params);
  }
 
+ SECTION("Postgis select from empty table")
+ {
+ mapnik::parameters params(base_params);
+ params["table"] = "test_empty_table";
+ auto ds = mapnik::datasource_cache::instance().create(params);
+ REQUIRE(ds != nullptr);
+ mapnik::query qry(ds->envelope());
+ auto featureset = ds->features(qry);
+ auto feature = featureset->next();
+ CHECK(feature == nullptr);
+ }
+
  SECTION("Postgis dataset geometry type")
  {
  mapnik::parameters params(base_params);
@@ -304,9 +316,9 @@ TEST_CASE("postgis") {
  auto feature = featureset->next();
  CHECKED_IF(feature != nullptr)
  {
- CHECK(feature->get("t_pixel_width").to_string() == "numeric");
- CHECK(feature->get("t_pixel_height").to_string() == "numeric");
- CHECK(feature->get("t_scale_denom").to_string() == "numeric");
+ CHECK(feature->get("t_pixel_width").to_string() == "double precision");
+ CHECK(feature->get("t_pixel_height").to_string() == "double precision");
+ CHECK(feature->get("t_scale_denom").to_string() == "double precision");
  }
  }