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PODjango __unicode__ and FK is very slow
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copied!<p>if I write something like</p> <pre><code>class Chip(models.Model): name = models.CharField(max_length=16) shortname = models.CharField(primary_key=True, unique=True, max_length = 16) def __unicode__(self): return self.shortname class ChipStepping(models.Model): stepping = models.CharField (max_length=16) ChipShortname = models.ForeignKey('Chip', db_column="ChipShortname") def __unicode__(self): return "%s:%s" % (self.ChipShortname, self.stepping) class ComponentType(models.Model): name = models.CharField (max_length=32) ChipStepping = models.ForeignKey('ChipStepping', db_column="ChipStepping") def __unicode__(self): return "%s(%s)" % (self.name, self.ChipStepping); class ComponentVendor(models.Model): name = models.CharField (unique=True, max_length=16) products = models.ManyToManyField('ComponentType', through='ComponentVendorProduct', related_name='vendors') def __unicode__(self): return "%s" % (self.name) class ComponentVendorProduct(models.Model): ComponentVendor = models.ForeignKey('ComponentVendor', db_column="ComponentVendor") ComponentType = models.ForeignKey('ComponentType' , db_column="ComponentType") </code></pre> <p>And try to create an admin page for ComponentVendor</p> <pre><code>class ProductInline(admin.TabularInline): model = ComponentVendor.products.through extra = 0 class ComponentVendorAdmin(admin.ModelAdmin): inlines = [ProductInline] list_filter = ['products__name'] exclude = ['products'] admin.site.register(ComponentVendor, ComponentVendorAdmin) </code></pre> <p>The resulting page can take upwards of 30 sec. to load From some debugging I've done, I found that it repeatedly makes redundant singular queries for ChipStepping and then Chip, with the same argument in the where clause instead of intelligently building a query that can lookup all the data.</p> <p>This problem is reduced if I remove the foreign key references from the <strong>unicode</strong> functions of ChipStepping and ComponentType</p> <p>If there are enough entries in ComponentVendorProducts for a vendor I click on in the admin page, the page can take several minutes!</p> <p>Is there a way I can reduce the number of database hits on the admin page?</p>

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