diff --git a/src/obidmscolumn.c b/src/obidmscolumn.c
index bdfc4fb..dfedaaf 100644
--- a/src/obidmscolumn.c
+++ b/src/obidmscolumn.c
@@ -23,6 +23,7 @@
 #include <sys/mman.h>
 
 #include "obidmscolumn.h"
+#include "obidmscolumn_idx.h"
 #include "obidmscolumndir.h"
 #include "obidms.h"
 #include "obitypes.h"
@@ -826,8 +827,8 @@ OBIDMS_column_p obi_create_column(OBIDMS_p     dms,
 }
 
 
-OBIDMS_column_p obi_open_column(OBIDMS_p dms,
-								const char* column_name,
+OBIDMS_column_p obi_open_column(OBIDMS_p     dms,
+								const char*  column_name,
 								obiversion_t version_number)
 {
 	OBIDMS_column_p 		    column;
@@ -863,6 +864,12 @@ OBIDMS_column_p obi_open_column(OBIDMS_p dms,
 	if (column != NULL)
 	{
 		(column->counter)++;
+		if (obi_close_column_directory(column_directory) < 0)
+		{
+			obi_set_errno(OBICOL_UNKNOWN_ERROR);
+			obidebug(1, "\nError closing a column directory");
+			return NULL;
+		}
 		return column;
 	}
 
@@ -985,7 +992,7 @@ OBIDMS_column_p obi_clone_column(OBIDMS_p         dms,
 {
 	OBIDMS_column_p   column_to_clone;
 	OBIDMS_column_p   new_column;
-	index_t 		  nb_lines;
+	index_t 		  nb_lines = 0;
 	index_t			  nb_elements_per_line;
 	OBIType_t		  data_type;
 	size_t 			  line_size;
@@ -1003,10 +1010,10 @@ OBIDMS_column_p obi_clone_column(OBIDMS_p         dms,
 
 	nb_elements_per_line = (column_to_clone->header)->nb_elements_per_line;
 
-	if (clone_data)
+	if (clone_data && (line_selection == NULL))
 		nb_lines = (column_to_clone->header)->line_count;
-	else
-		nb_lines = get_line_count_per_page(data_type, nb_elements_per_line);	// minimum line count corresponding to one memory page
+	else if (clone_data && (line_selection != NULL))
+		nb_lines = (line_selection->header)->line_count;
 
 	new_column = obi_create_column(dms,
 								   column_name,
@@ -1035,15 +1042,26 @@ OBIDMS_column_p obi_clone_column(OBIDMS_p         dms,
 
 	if (clone_data && (line_selection == NULL))
 	{
+		if ((new_column->header)->data_size != (column_to_clone->header)->data_size)
+		{
+			obi_set_errno(OBICOL_UNKNOWN_ERROR);
+			obidebug(1, "\nError cloning a column: the sizes of the data source and destination are not equal: source %zu bytes, destination %zu bytes.",
+					(column_to_clone->header)->data_size, (new_column->header)->data_size);
+			return NULL;
+		}
+		// Copy all the data to the new column
 		memcpy(new_column->data, column_to_clone->data, (column_to_clone->header)->data_size);
 		(new_column->header)->lines_used = (column_to_clone->header)->lines_used;
 	}
 	else if (clone_data && (line_selection != NULL))
 	{
 		line_size = obi_sizeof((new_column->header)->stored_data_type) * (new_column->header)->nb_elements_per_line;
-		for (i=0; i<((line_selection->header)->lines_used); i++)
+		// Copy each line at the right index to the new column
+		for (i=0; i<nb_lines; i++)
 		{
-			index = *(((index_t*) (line_selection->data)) + i);
+			// Get the index in the line selection column
+			index = obi_column_get_index(line_selection, i);
+			// Copy the line at the index in the column to clone to the new column
 			memcpy((new_column->data)+(i*line_size), (column_to_clone->data)+(index*line_size), line_size);
 		}
 		(new_column->header)->lines_used = (line_selection->header)->lines_used;
@@ -1121,16 +1139,22 @@ int obi_truncate_column(OBIDMS_column_p column)	// TODO is it necessary to unmap
 	multiple = ceil((double) (ONE_IF_ZERO((column->header)->lines_used) * (column->header)->nb_elements_per_line * obi_sizeof((column->header)->stored_data_type)) / (double) getpagesize());
 	new_line_count = floor((((int) multiple) * getpagesize()) / ((column->header)->nb_elements_per_line * obi_sizeof((column->header)->stored_data_type)));
 
-	// Check that it is actually greater than the current number of lines allocated in the file, otherwise no need to truncate
-	if ((column->header)->line_count == new_line_count)
+	data_size = obi_array_sizeof((column->header)->stored_data_type, new_line_count, (column->header)->nb_elements_per_line);
+
+	// Check that it is actually greater than the current data size, otherwise no need to truncate
+	if ((column->header)->data_size == data_size)
 		return 0;
+	else if ((column->header)->data_size < data_size)
+	{
+		obi_set_errno(OBICOL_UNKNOWN_ERROR);
+		obidebug(1, "\nError truncating a column: The current data size seems smaller than needed.");
+		return -1;
+	}
 
 	// Get the column file name
 	column_file_name = build_column_file_name((column->header)->name, (column->header)->version);
 	if (column_file_name == NULL)
-	{
 		return -1;
-	}
 
 	// Open the column file
 	column_file_descriptor = openat((column->column_directory)->dir_fd, column_file_name, O_RDWR);
@@ -1154,7 +1178,6 @@ int obi_truncate_column(OBIDMS_column_p column)	// TODO is it necessary to unmap
 	}
 
 	// Truncate the column file
-	data_size = obi_array_sizeof((column->header)->stored_data_type, new_line_count, (column->header)->nb_elements_per_line);
 	file_size = (column->header)->header_size + data_size;
 	if (ftruncate(column_file_descriptor, file_size) < 0)
 	{
@@ -1246,7 +1269,7 @@ int obi_enlarge_column(OBIDMS_column_p column)
 		return -1;
 	}
 	old_data_size = (column->header)->data_size;
-	new_data_size = old_data_size * COLUMN_GROWTH_FACTOR;
+	new_data_size = obi_array_sizeof((column->header)->stored_data_type, new_line_count, (column->header)->nb_elements_per_line);
 	header_size = (column->header)->header_size;
 	file_size = header_size + new_data_size;